RSS and Atom feeds, also know as 'syndication', are a way of having a special reader keep track of the latest news from some area of a web site; RSS and Atom are different formats for the feed information. But then, if you're reading this you probably already know all that.
DWiki provides Atom feeds for recently changed pages and recent comments. It doesn't currently support RSS feeds, although it may in the future. (Most feed readers should support Atom format feeds, and if they don't they should be upgraded to do so.)
At the bottom of every page supporting Atom feeds, there is a 'Atom Syndication' toolbar that has appropriate links. What they are feeds for depends on what they are attached to:
Unless your feed reader is unusually featurefull, Atom feeds are unauthenticated and so will not pick up any restricted content. (To pick up restricted content, the feed reader needs to give the DWiki server a valid authentication cookie.)