wow! wasn't gonna cheat here.
Just curious in understanding what you mentioned here. Most of the stuff is going off my head, as I'm new to python :)

What exactly is this code doing?

this will throw TypeError if values other than int, float are passed
not point of checking the range of numbers if the type is coming invalid.
alternatively - you can use isinstance

Also, why would you 'return 1' if either of a,b is 0 ?

or probably @qavaxb is just making sure that only int, float, complex numbers get multiplied and not others, althought the question doesn't states so.