kW vs kWh

kW (kilowatts) measures power, how much cooling a unit delivers or electricity it draws at a moment. kWh (kilowatt-hours) measures energy, how much electricity you actually used over time, which is what your bill charges for.

Aircon sizing talks in cooling kW: a "7kW split" delivers 7kW of cooling. Confusingly, that same unit might draw only 2kW of electrical power thanks to the refrigeration cycle. Run it for 3 hours and you've used 6kWh of energy, multiply by your tariff (say 32c/kWh) and that session cost about $1.92. Keep the two straight and power bills stop being mysterious.