That's 4.5 kilowatt-hours per day. I.e. in a day, it draws 4.5 kWh of energy.
A watt is a unit of power. A watt-hour is a unit of energy. 1 Wh = 1 W x 1 h. Similarly, 1 kWh = 1 kW x 1h. A 200-watt motor left on for an hour will draw 200 Wh of energy. A 200-watt motor left on all thetime will draw 200 W x 24 h = 4.8 kWh of energy per day.