Shortened form of "¿Y qué?", analogous to "So?" and "So what?"
Also directly matches with "And?"
Related:
#456973 ¿Y qué?
(jpn) で?
> (jpn) で?
I suspect that this wouldn't be considered a sentence.
I wonder, too, about the English item.
This is the type of thing that would make a much better example as part of a dialog.
Ok