What does 'SCV' mean?

From the Starcraft 1 manual (where the unit debuted), emphasis mine:

SCV Role: Space Construction Vehicle
 Armament: Fusion Cutters

Initially used during the reconstruction of the Tarsonian Orbital Platforms, the T-280 SCV (Space Construction Vehicle) became a staple in intra-Colonial construction and engineering due to its ability to perform a multitude of tasks, including the construction of new buildings and the transportation of raw resource materials. It is this versatility, and an unmatched reliability, that make the SCV an invaluable tool in rapidly establishing Marine encampments and strike bases on any terrain.

Edit: I found a picture of a German version of the Terran Tech Tree.

WBF stands for Weltraumbau-Fahrzeug (or Weltraumbaufahrzeug)

It stands for 'Space Construction Vehicle'. Heres a link