Once upon a time the internet was a collection of fairly static pages that people went and browsed. Thus the browser (Netscape, Internet Explorer, Firefox etc) became a key tool.
These days there are a lot more sites that offer up to the minute news (the BBC, FT, Google News, BizEd and blogs) and the RSS newsfeed is as useful for dealing with these as the browser is for static pages.
Basically what a newsfeed does is bring together in one place the latest updates from all the news and updating sites you want to check on a regular basis.
There are several newsfeeds, just as there are several browsers, but as a starting point a particularly user-friendly one is Bloglines.