RSS stands for Really Simple Syndication. Many sites, including the Freightliner Run Smart Hour, publish an RSS feed. And many Internet users, perhaps including yourself, use an RSS reader to receive that feed. An RSS reader is a small program that goes out online automatically, sees if there is new content on the site with the feed.
Many browsers, such as Microsoft's Internet Explorer 7 and Mozilla's Firefox, have RSS readers built into them, like smart bookmarks.