Walls

In online competitive shooter games, walls can be slang for ESP wall hacks. The script based hack allows the user to have a visual box outlining enemy players, the box can be seen through walls or any surface from anywhere in the game world. The hack is most commonly used in competitive shooters to give an advantage of enemy position awareness 24/7 but has been seen in other online games not primarily for competitive play.

Bro he was tracing me with his aim, dude probably has walls.