RSS is an acronym for Really Simple Syndication it is a family of web feed formats used to publish frequently updated works such as blog entries, news headlines, audio and video in a standardized format. To put it simply, the creator of a blog puts an RSS program on his or her blog which then makes the content of the blog posts available to be aggregated by an aggregator, such as Google Reader. This process is sometimes referred to as syndication. The information that is aggregated is called a feed. It is my experience that aggregators come and go, so you might want to stick with the larger and more established ones. You might also see an alternative syndication format called "Atom." Both RSS and Atom may be present in the same website. Usually both formats are represented by the standard orange square with white radio waves, like this:
The advantage of using a reader or aggregator is that you avoid having to individually open the sources. Most aggregators provide some sort of preview mode, where you can read either the whole post or a portion before actually going to the website. If you monitor a large number of sites, you may begin to get overwhelmed with the number of feeds you receive each day. My suggestion is this, don't feel obligated to review every one, every day.
You can also use an online program such as WatchThatPage, to get feeds from web pages that do not have either type of syndication.