what is a kilowatt hour?
A kilowatt is 1000 watts which is a measure of power. A kilowatt-hour is a measure of the amount of energy a certain machine needs to run for one hour. So if you have a 1000 watt drill it takes 1000 watts (or one kW) to make it work. If you run that drill for one hour you’ll have used up one kilowatt of energy for that hour or one kWh.