It is placed on the dashboard and it shows the "engine spins", that is to say, the rotation speed of the engine. It varies depending on how much the driver is pressing on the accelerator, no matter whether the car is moving or not. Through the transmission, the acceleration will be linked to the wheels, and this will allow the car to advance.
The back lights behind my RPM gauge are completely out and part of the ones behind the miles per hour. Also random buttons on the radio and AC are out as well. I don't think it's a cluster issue otherwise it would be the whole thing and not just certain buttons.