You mean, space? You can actually go there? I mean, I made a sword out of a meteor that came falling down once upon a time, but I never ever thought of being able to go there.

[Then again, Sokka never thought of being able to fly before meeting Appa and Aang, so...]

Well, it's some sort of magic stuff that manipulates the ground, rocks, and—if you're good enough—metal. Toph was able to pull up solid chunks of stone from the ground and hurl them at people, fling us into the air like a catapault would by moving the ground underneath us, and able to tear holes in metal.