A devotional, reph, is like a thought for the day. A lot of people use it in conjunction with their Bible to do Bible study or to have an encouraging theme to think about throughout their day.
Sometimes I use the devotionals I read for specific information in the Bible--such as "What does the Bible say about sex before marriage?"--that I might not already know the Biblical passage for. Also, devotionals tend to be written in a simpler language than most Bibles are, which makes for an easier-to-understand read.
But basically it's a Bible thought for the day, that is maybe a couple pages long at the longest, which allows someone on a busy schedule to read their Bible and understand it in easily digestable bits.
I hope this helps. Cool thread!