Why is the function of addoneto(x)

Question

please explain
https://code.sololearn.com/cRGs73Lju6Ah/?ref=app

Answer 1

addOneTo gets a copy of x, not x itself. So changing num won't change x, and that's usually a good thing!

Answer 2

I think it is just showing you that x is used and passed into addoneto but not altered and returned back as x, that is why when printed x is 5 and not 6.