I have in mind natural languages, like what you are now reading and what you'd write in response to me. Various people have been constructing languages for some centuries, but conlanging got a big boost in the late 19th cy. with Volapük and Esperanto, both of which were intended as international auxiliary languages.
Some people have constructed languages as a hobby, notably J.R.R. Tolkien. He went on to construct worlds for the speakers, and then stories in those worlds: the Lord of the Rings series.
Constructed languages in fantasy & SF | Anne Lyle
Mark Rosenfelder's Metaverse -- including lots of stuff on conlanging
List of constructed languages - Wikipedia
If you wish to construct a conlang for your story, you could start with what Mark Rosenfelder calls a "naming language". Construct only what's necessary: sounds, way of spelling them, and some vocabulary and grammar -- you will usually need only noun phrases. Unless you have names that are whole sentences. Instead of "Beaver Creek", "Beavers Love This Creek" -- you'll need a full-scale conlang for that.
As to phonology or language sounds, a lazy way of indicating a different one is to use lots of apostrophes. But one could look at how languages vary. Some languages have sounds that others don't, others make distinctions that others treat as alternations of the same high-level sound or phoneme ("allophones"), etc. If you want a quick comparison of phonology possibilities, WALS Online - the World Atlas of Language Structures is a good place to look. Wikipedia articles on individual languages are also a good place to look, though you may have to do a lot of looking to get a good picture.
For instance, in Old English, initial and final f and medial v were treated as allophones of the same phoneme, something that survives in some irregular plurals: wolf - wolves, knife - knives, ... But English got oodles of Old-French words from the Norman conquerors, words where f vs. v sounds made a difference: fealty - veal, ... That split the Old English f/v phoneme into two phonemes, f and v.
Some languages, like Finnish, are like Old English f vs. v for most consonants -- primarily voiceless but made voiced in some environments. By comparison, English distinguishes two voicings, Thai three voicings of stop consonants (p, t, k), and Hindi four voicings of them. Thai's three voicings are voiceless, voiceless aspirated (with a puff of air), and voiced. English also has the first two, but treats them as allophones: stun - ton, spin - pin, skin - kin.
Some languages distinguish places of articulation (where a consonant's sound is made) that others don't. Hindi, like several other South Asian languages, distinguishes between tongue-on-teeth t and tongue-on-roof-of-mouth t. Arabic distinguishes between high-in-throat k and low-in-throat k, usually written q in the Roman alphabet. Qatar, for instance. Japanese does not distinguish l and r, thus "Engrish".
Some languages have incomplete sets of sounds. For instance, Arabic has b but not p.
Turning to vowels, some languages distinguish lots of them, like English, while some distinguish very few, like Arabic with a, i, u. But in the few-vowels case, the vowels can sound like e and o in some environments.
Also, some languages, like Finnish and Arabic, distinguish long and short vowels, while others don't.
Allowable consonant clusters vary. English allows a lot of them, though with some limits. Only a few three-consonant clusters, for instance: strip, spring, script.
Syllable structure varies from vowel or consonant-vowel only to allowing a few final consonants (not all at once!) to allowing many of them, as English does.
Turning to orthography or spelling, look at what different languages have done with our alphabet. English exclusively uses letter clusters to represent additional sounds, while many other languages use extra marks, though often alongside letter clusters. As an example, consider the spelling of the "ch" sound. English uses "ch", French uses "tch", German uses "tsch", Spanish uses "ch", Italian uses "ci", Polish uses "cz", Czech uses "c" with a small v on top, and Croatian has two, a Czech-like one, and a c with a forward accent on top.
I think I'll leave off here.
Some people have constructed languages as a hobby, notably J.R.R. Tolkien. He went on to construct worlds for the speakers, and then stories in those worlds: the Lord of the Rings series.
Constructed languages in fantasy & SF | Anne Lyle
Mark Rosenfelder's Metaverse -- including lots of stuff on conlanging
List of constructed languages - Wikipedia
If you wish to construct a conlang for your story, you could start with what Mark Rosenfelder calls a "naming language". Construct only what's necessary: sounds, way of spelling them, and some vocabulary and grammar -- you will usually need only noun phrases. Unless you have names that are whole sentences. Instead of "Beaver Creek", "Beavers Love This Creek" -- you'll need a full-scale conlang for that.
As to phonology or language sounds, a lazy way of indicating a different one is to use lots of apostrophes. But one could look at how languages vary. Some languages have sounds that others don't, others make distinctions that others treat as alternations of the same high-level sound or phoneme ("allophones"), etc. If you want a quick comparison of phonology possibilities, WALS Online - the World Atlas of Language Structures is a good place to look. Wikipedia articles on individual languages are also a good place to look, though you may have to do a lot of looking to get a good picture.
For instance, in Old English, initial and final f and medial v were treated as allophones of the same phoneme, something that survives in some irregular plurals: wolf - wolves, knife - knives, ... But English got oodles of Old-French words from the Norman conquerors, words where f vs. v sounds made a difference: fealty - veal, ... That split the Old English f/v phoneme into two phonemes, f and v.
Some languages, like Finnish, are like Old English f vs. v for most consonants -- primarily voiceless but made voiced in some environments. By comparison, English distinguishes two voicings, Thai three voicings of stop consonants (p, t, k), and Hindi four voicings of them. Thai's three voicings are voiceless, voiceless aspirated (with a puff of air), and voiced. English also has the first two, but treats them as allophones: stun - ton, spin - pin, skin - kin.
Some languages distinguish places of articulation (where a consonant's sound is made) that others don't. Hindi, like several other South Asian languages, distinguishes between tongue-on-teeth t and tongue-on-roof-of-mouth t. Arabic distinguishes between high-in-throat k and low-in-throat k, usually written q in the Roman alphabet. Qatar, for instance. Japanese does not distinguish l and r, thus "Engrish".
Some languages have incomplete sets of sounds. For instance, Arabic has b but not p.
Turning to vowels, some languages distinguish lots of them, like English, while some distinguish very few, like Arabic with a, i, u. But in the few-vowels case, the vowels can sound like e and o in some environments.
Also, some languages, like Finnish and Arabic, distinguish long and short vowels, while others don't.
Allowable consonant clusters vary. English allows a lot of them, though with some limits. Only a few three-consonant clusters, for instance: strip, spring, script.
Syllable structure varies from vowel or consonant-vowel only to allowing a few final consonants (not all at once!) to allowing many of them, as English does.
Turning to orthography or spelling, look at what different languages have done with our alphabet. English exclusively uses letter clusters to represent additional sounds, while many other languages use extra marks, though often alongside letter clusters. As an example, consider the spelling of the "ch" sound. English uses "ch", French uses "tch", German uses "tsch", Spanish uses "ch", Italian uses "ci", Polish uses "cz", Czech uses "c" with a small v on top, and Croatian has two, a Czech-like one, and a c with a forward accent on top.
I think I'll leave off here.
