How to work with kivy properties?

Question

Python

Hello.
I can't figure out how properties work.
Suppose there is,
name = NumericProperty()
I prescribe somewhere in theory, a function should be called (it is not called for me) (the function is in the class where name is)
NameClass.name = 5

def on_name(self):
    pass

and so, I do not understand what parameters the function should have; how to get the value of name; is it possible to change name outside the class where it is declared; how the function should be called (I know that it is called when the name changes); how to correctly assign a new value to name.
I will also be grateful if you tell me some other subtleties about which I did not ask, but which are important.