The Feedburner folks tend to write in marketingspeak, but it is a useful service.
RSS stands for Really Simple Syndication. There are some cool things you can do with RSS, but it may depend on what your blog hosting service offers. Click on my blog link below. I offer two feeds and you can look at them via Feedburner. The short feed just gives a title and summary, and I use a Feedburner feature to add my latest Flickr picture. The full feed contains the entire entry complete with pictures.
Feedburner subscribers generally get a daily e-mail update that shows which blogs (or other content) they watch has been updated. If the subscriber gets my full feed, then it's all right there in e-mail. If they get the short feed, then they need to click on a link to go to my site to read the entire entry.
Click on the RSS links to see what a raw feed looks like. Most blogging services create that for you. The help section of your blogging service should show you how to get started with RSS.
RSS isn't just for blogs. You can watch the latest headlines from your favorite news sites or keep an eye on podcasts that interest you.