Question

What makes metals, in particular, good conductors of electricity?

Answer 1

Free electrons makes the good conductor for electricity

Answer 2

Electric current is the flow of electrons in a wire. In metals, the outer electrons of the atoms belong to a 'cloud' of delocalised electrons. They are no longer firmly held by a specific atom, but instead they can move freely through the lattice of positive metal ions, these factors makes them  a good conductor of electricity .