It depends on what you referring to. If you ask why the coconut fall to the ground from the coconut tree, then I can answer. The coconut falls the the ground from the coconut tree because the fruit gets heavier when the fruit ripens.
Because the gravity force that exist in this world. The coconut has its own weight, so that is why the follow the gravity by falling down from the coconut tree. Other than that, because the contain inside the coconut getting heavier make them easily detachable from the tree and falling down.