My simple question is what is it used for?

Hmm... your question has been sitting around here some time...

I cannot answer your question, since I don't have pp and am running a system which doesn't have EXE files. But to find out you could read the documentation of pp, dig into its code, or run the program with that funny file name and watch its outcome. Maybe you want to backup your data first :-) If you have a means of comparing that EXE file to the expected and regularily produced App.exe, that could give you more hints.

BTW, lots of programs create temporary files, itermediate files or files whose purpose has been forgotten...

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}