The User Map tab is a way for you to see how the Joomla users are mapped to Facebook on your site. The "Joomla User" column will display the Joomla user's name with a link to the User Manager area for that user. The "Provider User" column shows the user's unique social network avatar with a link to the publicly viewable social network profile from either LinkedIn, Twitter, Facebook, etc. The "Sent Requests" column is the number of Facebook requests that this user has sent to their Facebook friends from your site; the "Received Requests" column is the number of Facebook requests that this user has received from friends or any administrator requests from your site. "FB App Authorized" indicates whether the user has removed your FB application from their allowed Facebook Apps.
If you've been using a different Facebook Connect component for managing Facebook, you can use the "Import Connections" button to migrate these users to JFBConnect. You must first have the JFBConnect Profile Plugin enabled that is associated with the extension you want to import connections from. Currently, only the JomSocial JFBConnect Profile plugin supports importing connections. Others will be added later as requested.