RSS stands for Real Simple Syndication, among other things. It's a way of converting text on a website into a "feed." That feed can be combined with others to help you gather information from all of your favorite websites and read them at one place (your feed reader).
Basically, you're taking your daily web-surfing and converting it into a readable format that looks a lot like your e-mail. It can be a huge timesaver, because it saves you from having to go searching for material. Your "reader" brings the news to you.
And if you want to know what's going on in the recruiting blogosphere, you might check out the page that has all the feeds.