Function of cerebellum
The cerebellum coordinates movement and maintains equilibrium and muscle tone.
It compares what you thought you were going to do (according to motor cortex) with what is actually happening in the limbs (according to proprioceptive feedback) and corrects the movement if there is a problem through a complex regulatory feedback system.
It receives somatosensory input from the spinal cord, motor information from the cerebral cortex, and balance input from the vestibular organs.
It integrates all this information and aids in organizing the range, velocity, direction, and force of muscular contractions to produce steady volitional movements and posture.
It does so by constantly screening its sensory inputs and modulating its motor outputs.