What is a BIN of a vehicle?

You're probably looking for the VIN, which is Vehicle Identification Number. It's ususally a stamped plate on the dash of the car right in front of the driver at the bas of the windshield (as well as other less obvious places according to the make and model.)

It's basically a unique code every vehicle has that tells everything from where the car was built to what the engine type and trim package of the vehicle is. These numbers are used by insurance companies to help classify rates, for registering the vehicle with the DMV, or for mechanics to be sure they get the right parts for each particular engine type that might be found in that same car.