The Vandenberg AFB Space Launch Complex is a launch complex located in the US Vandenberg Air Force Base (AFB). It is composed of several luanch sites (SLC-2, SLC-3, etc.).
SLC-2, the Space Launch Complex 2, is an active rocket launch site at Vandenberg Air Force Base, in California, USA. It consists of two launch pads. The East pad (SLC-2E), which has been demolished, was used for Delta, Thor-Agena and Thorad launches between 1966 and 1972. The West pad, SLC-2W, has been used for Delta, Thor-Agena, and Delta II launches since 1966, and is still in service with the Delta II.
SLC-3, the Space launch Complex 3, consists of two pads, SLC-3E (East) and SLC-3W (West). The East-West coastline at Vandenberg allows SLC-3 to launch over-ocean polar trajectories that avoid landfall until passing over Antarctica. (By contrast, Cape Canaveral has a North-South coastline permitting over-ocean launches into standard orbits.)
AFB means 'Air Force Base'.