A special purpose vehicle is a separate legal entity with separate assets and liabilities created by companies or organizations in order to isolate the financial risk of a very specific objective or project. This completely separates the operation of the parent company and the SPV, including if either goes bankrupt.
If there is a project that will involve significant risks, a company might create an SPV in order to legally isolate the risks of this specific project from the rest of the company. This also allows other investors to invest specifically in this project rather than the company as a whole.
A company may create a special purpose vehicle (SPV) to own properties in order to avoid paying high property sales tax when later selling of those properties. By selling the SPV instead, the company would only be subject to capital gains tax, which may be lower than the property sales tax, allowing the company to minimize the tax burden on the sale.
Some assets are very complicated to transfer, so a company might create an SPV that owns the asset and then they will sell that SPV in order to complete the transfer process.