it just means the system is capable of emitting that much force in some form within the time period specified, and the thing that is missing from teh understanding is that this must be applied to a load, which has inertia in some form, and the higher the watt/hour the faster you can overcome that inertia (steady state with no change of velocity, be that linear or rotational) or forces of torsion which underlie all forms of resistive heat