Power is the rate in which work is done, much like kilometers (or miles) per hour is a rate. The SI unit for power is the Watt, and it’s defined as one joule per second. Whether it takes you three seconds or one second to move 100kg to 1m above the ground, you use the same amount of energy. However, it requires more power to do it in one second.
When it comes to electric power, “work done” refers to the ability of the circuit to transform electrical energy into something else, like heat, motion or sound. “Work done” can also refer to transforming some other form of energy into electrical energy, as in a battery, which converts chemical energy to electrical energy.
As power is work done per unit time, with a little bit of math we find that electric power is defined as voltage times current: P = V x I.