In the quoted code,  $c is a lexical (or my) variable initialized from the second item of the argument list of the  hello() and  end() functions — actually, from the code it seems more appropriate to call them "methods" rather than functions. Again from the context of the code, I'd guess the  $c variable in both cases is an object reference. (Update: Please see perlobj.)

The precise name is not important. It could as well have been  $xyzzy or  $some_name_that_has_meaning_for_me just as long as the naming was consistent throughout the function/method.