Wallhacking allows a player to see through solid objects. Wallhacking relies on the fact that an FPS server usually sends raw positional information for all players in the game.
sXe Injected calculates for each player which other players it can see or not, the information of those players who are not visible are not sent to the client, this blocks wallhacks, ESP and other cheating tools based on these positional information.
Anti-Wallhack is a server-side feature, a cheat operates in the player's computer, this means that there is no cheat that can override this protection.
Anti-Wallhack don't hide teammates, deads or entities on default mode due to a higher server processor cosumption. Anyway if you want to block all of them you have some cvars:
__sxei_awhforteam 1 (blocks teammates)
__sxei_awhfordead 1 (blocks deads)
__sxei_awhforent 1 (blocks entities)
Anti-SpeedHack
Anti-NoFlash
Anti SlowHack
Global Ban