If I’m recognizing the registry key correctly, that restores the Windows 10 context menu in the file Explorer (right mouse button menu on a file in the file list).
The Win 11 version of that menu is abbreviated and hides a lot of common and useful features under a second “more options…” click.
Yes, that’s right, MS dumbed down the Windows Explorer context menu. Using that registry hack was one of the first things I did after upgrading to Win 11.