The unit for power in electricity should be watt. The power show how many energy transferred during a time and the SI unit would be joule per second.
The bill is charging for the amount of energy. The energy could be calculated by multiplying the power with time. In this case, the power in kilo watt will be multiplied by the duration in hour which make the kilowatt hour.
Kilowatt hours is a measure of the electricity consumed by a device during a certain period of operation.
Watt-hour is a unit of energy measurement and hour is a unit of time. One Watt-hour is the amount of energy required to power a 1 Watt load for 1 hour.
The power shown on each device indicates its power for a period of 1 hour. For example, a device with a power of 5400 W (Watts) will consume that power in one hour. The higher the power of a device, the higher its energy consumption. And the longer the device stays on, the more it will consume.
