I know it's a completely smoothbrain question, but can someone explain wattage to me? My power went out for two weeks during a snowstorm last year, so I'm picking up a power supply and an indoor heater.

Thing is, the power supply is labeled "500W" and the heater is "1500W". Does this mean it won't be able to power the heater? Or will it work, but just drain the power 3x as fast? For reference, the power supply is a Jackery 500.