This is polyglot code : it works in several languages. This one is valid in in C, Python, Perl, Ruby, Befunge-93, and Brainf*ck.
In Python/Perl/Ruby the only code that gets executed is
This means it shows 404 then exists the page.
The rest is commented code because of the '#'.
In C, the code executed code is:
Brainf*ck is an esoteric programming language which only read 8 symbols :
[ ] < > + - . , so the code read is :
+-> ++++++++ [>++++++<-] >++++. ----. ++++. >.
I didn't come up with this on myself, but had the same curiosity some time ago and found this answer https://meta.stackoverflow.com/a/252187/2047249 on meta stackoverflow.
That answer explains it better than I ever could.