KWh means KiloWattHour, therefore 6KWh means 6KiloWatts used (or produced) in one hour (6,000 Watts per hour). 1000Watts is 1KW.
Think in terms of a light bulb. A 100watt light bulb would have to be on for 10 hours to consume 1KWh of electricity ( 100Watts x 10 = 1000 which is a KiloWatt ) .
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