Flow Navigation can be added to flow screen components to provide a way to specify what kind of navigation should take place upon things like button clicks.
There are three kinds of Flow Navigation:
1. Move the Flow (equivalent to clicking Next, Previous, or Finish)
2. Load a Web URL into another tab (Lightning Experience only)
3. End the flow by replacing it with another Salesforce page (Lightning Experience only)
When a component has Flow Navigation added to it, it inherits the following attributes:
Determination of which destination to take is implicit: the navigation code expects either 0 of the destination attributes to be passed in (in which case no navigation will occur) or 1 will be passed in. If you specify two or more, an error message will appear.
More information on the underlying Lightning Navigation technology is available here.