Question

Why are metals good conductors of electricity physics answer?

Answer 1

because of presence of free electrons

Answer 2

due to their atomic configuration, metals have free electrons in their outer-most shell, they act as a medium for displacement of charge due to which it conducts electricity

this is a relatively simpler form of the explanation but there are many other factors like the shielding effect and nuclear influence on the valence electrons. knowing these will help you understand why unlike metals, almost all non metals are non-conductors of electricity.