RSS feeds are a simple way to keep up with current information from a variety of sources. Instead of stopping by many different sites to check for new content, you can simply ask these sites to send new postings straight to your computer. You'll need to sign up for an aggregator (or "reader"); popular free readers include Bloglines and Google Reader.
A number of handy web-based tutorials can walk you through the startup process. Check these easy tutorials if you want more information:
RSS in plain English (video)
Getting Started with Google Reader (video)