kWh and kW, Watt-hours and Watts, a messy topic
Electric power is measured in Watts
Electric energy usage is measured in Watts over a period of hours, or Watt-hours
Power: 100-Watt light bulb vs. 30-Watt light bulb
Energy: How long the bulb is on. A 100-Watt bulb that's on for 10 hours uses 1000 Watt-hours or 1 kilo-Watt-hour, written 1 kWh.
A 3000-Watt microwave that runs for 2 hours uses 6,000 Watt-hours, or 6 kWh. Each appliance has a plate on it that shows how many Watts of power it uses. Knowing how long it’s on, estimate total energy kWh usage.
Average home uses 500 to 1000 kWh per month. Really efficient homes can use as little as 300 kWh.