Question

Power can be defined as

Answer 1

Rate of change of energy per unit time:
$$
\cfrac{\Delta U}{\Delta t}
$$
Where U is energy and t is time.

The units or Joules per unit time or Watts.

Make sense?

Answer 2

@ybarrap
also means the ability to do work
right?

Answer 3

Work is defined as
$$
\Delta W=F\cdot \Delta x
$$
Where F is force in Newtons and x is distance in meters. The units of which are Joules. The rate of doing work is power:

$$
\cfrac{\Delta W}{\Delta t}
$$