Multiple textures in the same Z axis?

[DShot]

I started AC to make my second map when ac_douze loaded in the startup and I've noticed one thing...



That's probably very old and newbie question, but how can I make multiple texture in the same Z axis? This wall in the picture seems to have 3 different textures.

I'm really curious about it. If you know how to make it plz reply, thx!