This show a more descriptive label for Pay To Yourself transaction entries in bitcoin QT. Showing the label of the first Output.
Before:
After:
Pay to yourself is common when using Bitcoin Core for tracking coins going from and to Watch-Only addresses. For example, in the case of TumblerBit, it will make it easier to see when a coins is transitioning throught different states: Wallet =>Alice Escrow => Alice Offer => Alice Offer Redeem.