This is a house-keeping test to examine the Core database tables for any unwanted orphaned records and references. Orphaned records are database entries that are no longer needed and should have been deleted along with their "parents". For example, when you delete a form, any references to that form ID should also be deleted. Orphaned records shouldn't cause problems, but add unnecessary clutter to your database.
If this test finds any problems, we'd appreciate it if you'd report them in the forums: it'll help us identify loopholes in the code.
Don't worry! Orphaned records are NOT a big deal. Just click the link that shows up and have them all removed. "Death to orphans". That's always been my motto.