Arg names in class and function code - Newbie question

[Lol]

HI all,
	Could anyone let me know - do the names you give as arguments HAVE to be
actual variable names?
e.g def readFile(filename,dir):
	blah blah
	return blah
or even class FileRead(filename,dir):
	def doSomething (self,this):
		yadda yadda
		return yadda

In the above examples do filename and dir have to be the name of the
variables to pass as args to the class/functions OR are they descriptive
so I can pass the real name of the file and directory?