So, this is /fill: So, most of what I know of the command is like this: /fill 1000 4 1000 900 4 900 TNT.

So, this is what happens: It fills the cord 1000 4 1000 to 900 4 900. It basically fills in the area of a specific region.

And then, after it fills in, you can do anything you want with it. Like you just filled it with TNT (Don’t try this unless you want a very lagged screen.) Then… You blow it up! KABOOM! Welp that was a huge explosion.