What happens when the forces acting on an object are not balanced

It creates the forces to be unbalanced. The one that happens to have more force will either pull or push. This is part of Newtons second law.

When two forces acting on an object are not equal in size, we say that they are unbalanced forces. If theforces on an object are unbalanced this is what happens : an object that is not moving starts to move. an object that is moving changes speed or direction