RSS stand for
Really Simple Syndication (RSS 2.0)
Rick Site Summary (RSS 0.91, RSS 1.0)
RDF Site Summary (RSS 0.9 and 1.0)...
RSS is a family of web feed formats, specified in XML and used for Web syndication. RSS is used by (among other things) news Web sites, weblogs and podcasting.
Web feeds provide web content or summaries of web content together with links to the full versions of the content, and other metadata. RSS, in particular, delivers this information as an XML file called an RSS feed, webfeed, RSS stream, or RSS channel. In addition to facilitating syndication, web feeds allow a website's frequent readers to track updates on the site using an aggregator.
You can find a tutorial on how to set up a RSS for your website step by step, along with alot of other useful information here:
http://www.xul.fr/en-xml-rss.html
Your web host will deteremine how many RSS Feeds you can have, most limit it to a max. of 3