Final answer:
A motion controller provides input to the computer by sensing the motion of your fingers and hands.
Step-by-step explanation:
The function of a motion controller is to provide input to the computer by sensing the motion of your fingers and hands. It allows users to interact with computer applications or games by translating their physical movements into digital commands. For example, a motion controller for a gaming console can detect the player's hand gestures and translate them into actions in the game.