It means that when you purchase an eligible electric vehicle (EV) or plug-in hybrid electric vehicle (PHEV) and you meet the income requirements, you can choose to transfer your tax credit to a registered dealer and get the FULL amount of the tax credit upfront as a reduction on the price of the vehicle.
For NEW vehicles: Depending on the vehicle, you could get $3,750 or $7,500 off of the purchase price at the time of the sale. This money can also be used as a down payment on the vehicle.
For USED vehicles: Depending on the vehicle, you could get $4,000 off of the purchase price at the time of the sale. This money can also be used as a down payment on the vehicle.