A quiet title is a very specific type of law suit that is filed to clean up the title of a property, so to speak.
It can happen in a couple of different circumstances. One is there is an interest in the property, or a claimed interest that the owner of the property does not recognize and wants eliminated as a matter of record.
Another common area in which a quiet title action might be filed is to quiet the title to a tax deed. Someone might acquire a title to a property at a tax deed sale, but insurance companies won’t insure that title until a quiet title action has been filed.