What is VL build?

As I was typing this question I realized that it might be an abbreviation for (Volume License). Could you please confirm this

That is correct.

or let me know what VL Build actually means.

VL Builds work with VLKs (Volume License Keys).

Volume license keys can be used to activate multiple installations of the software without any mechanism (such as a product activation mechanism) checking the total number of installations.

The license for the software will place restrictions on the use of the key. Typically the licence will limit the key to a fixed number of installations which must only be within the licensee's organisation and also place the licensee under an obligation to keep a record of the number of installations, keep the key confidential and possibly even require that the licensee organisation makes itself available for a software licensing audit to verify that its use of the key is within the terms of the licence. If a volume licence key becomes known and used outside of the organisation it is licensed to then this is regarded as software piracy.

Source

The accepted answer had been outdated when it was first posted. Since Vista, VLK is revamped to keep track of activation counts to combat software piracy. Gone are the days where leaked XP VLK would activate unlimited copies. VL build only differs in its license and activation methods (Retail keys vs VL keys, be it MAK or KMS). In fact, Windows will switch between Retail and VL channel at will according to the type of key you inserted.