This command toggles (enables and disables) noclip mode. In no clip mode your character does not collide with solid objects in the world, this allows you to move through walls, etc. This command is useful for getting unstuck from a location and accessing usually out-of-bounds locations.
togglecollision
ToggleCollision
The above command will enable noclip mode (allow you to move through walls). If you are already in noclip mode, this command will disable it.