Newton's second law states that the speed of acceleration of a moving object depends on the object's mass and the force being exerted on it. One instance of this is the understanding that it requires much more force to push a vehicle than to kick a soccer ball, for example.
Simply, Newton's second law represents the fact that the greater the mass of an object, the more force there is needed in order to move it. This explains why, for example, it requires one person to easily lift a box weighing five pounds but multiple people exerting more force collectively to lift a box weighing 100 pounds. Acceleration, or the speed of a moving object, can be calculated with the equation Acceleration = Force / Mass.