A Special-Purpose Vehicle or is a subsidiary of a company which is bankruptcy remote from the main organisation (i.e. protected even if the parent organisation goes bankrupt). The actions of an are usually very tightly controlled and they are only allowed to finance, buy and sell assets.
The purpose of a Special-Purpose Vehicle is to allow the parent company to make highly leveraged or speculative investments without endangering the entire company. If the goes bankrupt, it will not affect the parent company.