what is the rate at which electrical energy is converted to another form of energy  called ?

Any rate of energy is called "power".It could be the rate at which 1 pint of water loses gravitational potential energy as it falls from Niagara Falls.It could be the rate at which your body converts food into heat.It could be the rate at which your car gains kinetic energy when you floor the gas pedal.It doesn't have to involve electrical energy.

the rate is called power and its unit is voltage