News Feeds (com_newsfeeds) is a way to display content published by other sites. Give Joomla the address of a site's RSS or Atom feed and it will pull in the headlines and show them on your pages, refreshing them as the other site posts.
Feeds are organised into categories in the same way as articles, and there are menu item types for a single feed, for a list of the feeds in one category, and for a list of all feed categories. Feeds are added in the administrator under Components → News Feeds.
For a single feed in a module position rather than a full page, use the Feed Display module instead.