This tool allows you to rotate or move the selected face by any edge, or even using the face normal. It is super convenient and easy to use.
When you use the tool, it shows yellow lines for the closest edge.
You can drag with left mouse button, it will rotate the mesh.
Or you can drag by right-mouse button, it will move the faces along it.
After rotation or movement, you can also input numbers directly for exact angle or distance in the Left-Bottom menu.
Face Normal Mode :
You can press F key to switch to Face Normal Mode. It will show yellow lines for face normal instead of edges. You can then rotate the faces by normal lines, or move along them.
Just press F key once to toggle the mode.