Lists the TempDB usage per each active session.
It helps identifying the sessions that use the tempdb heavily with internal objects.
When the internal objects usage is high, the session is probably using big hash tables or spooling in worktables. It could be a symptom of an inefficient plan or a missing index.
Shrinking a TempDB full of internal objects will probably have no effect, because the engine will not release the deallocated space. The only possible alternative to restarting the service, is running DBCC FREESYSTEMCACHE('ALL'), that will clear all cached objects, including not only internal objects, but also cached query plans. Use it carefully on a production server.