RSS means Really Simple Syndication. It's a protocol that allows for sending and receiving data on the Internet. Typically it is used by newsagents to send their newsfeed around the world. Others simply have to know the URL of the feed and link it to a newsreader.
Ordinary people can link their blogs to an RSS feed provided by their hosts.
News readers are available everywhere. Typically Microsoft Outlook, FireFox, IE Google Reader are good examples of commonly available readers.