In the easiest language torque is the quantity used to measure the towing power of a car. In physics we all have read, torque is a force used to rotate objects that are to start a stationary object from rest to rotation.

So, in cars, it is the low-end power or the measure of vehicles power at a low acceleration which means for heavy vehicles (where there is less acceleration) torque is more and high speed is less.
Vehicles usually use torque to rotate the crankshaft which further initiates the whole transmission following the wheels.
The meaning of 480 lb-ft torque can be clarified by imagining a lug wrench tightening a bolt. If it has a 2 ft long handle and you put 100 lb of force on it, you are putting 200 lb-ft torque on the bolt.