What does the American ‘When you are through’ mean? But would more generally mean position or movement e.g. Is Superman if he fly through the air?

In British-English one is not through with it but “done with it” (informal) or “finished with it” (more proper.)

“Done” is considered less correct but is in common usage, I think again, it may be an earlier American-ism, though I am not sure.

I know that some Americans include a phrase that says, “When you are finished.” Although they’re relatively safe to use the word “when you are done,” the words itself are not necessarily offensive.

EDIT: “You have finished”, would be better. Again, again.

“When you have finished”

If given a chance to describe himself in 5 words he’d say that he wants to know what he wants.

If

he had to describe himself in five words, he’d say he’s curious. And would then forget to give you 4 more words.

, “and” and “full stop” at the start of the second sentence suggested a continuation which informally should be more explicit.

If I had

to describe myself in 5 words, he’d say he’s curious. And then forgets to give you 4 more words.

is even less correct as this compounds the error with an incorrect tense of “forget”