L3 on an Xbox controller refers to the left analog stick pressed down. It is equivalent to LS (left stick) on an Xbox One controller. The Xbox One controller also has an RS (right stick) button, which is equivalent to R3 on a PlayStation controller. The Xbox One Wireless Controller has a directional pad (D-pad) located between the left and right sticks. If the L3 button on an Xbox One controller stops working, it may need to be repaired or replaced.