The weight of the vehicle when not carrying any passengers, goods or other items. It includes the body (the heaviest version if there are alternatives) and all parts normally included with the vehicle when used on a road, but not the weight of the fuel or, if it is an electric vehicle, the batteries.
Kerbside Weight
The weight of the vehicle unladen and carrying no persons, but with a full tank of fuel and adequate supply of other liquids incidental to its propulsion, and any loose tools or equipment with which it is normally equipped, but not with the driver.
It therefore equates to the unladen weight plus the weight of a tank of fuel.