When a footballer kicks a ball, the ball moves in the direction of applied force. The footballer also experiences a force on his leg which is equal to the force he exerted on the ball.
the football player did not hit the ball hard
According to Newton's third law, when a body A exerts a force on another body B, B also exerts an equal and opposite force on A. Hence, while kicking a ball, the footballer's leg will experience the same magnitude of force it exerted on the ball and in opposite direction.