Metals are good conductors of electricity because of the kind of bond that exists between their molecules. The molecules of metals are held together by a metallic bonding. As such, the atoms of metals are encased by a horde of electrons that are constantly in motion. This horde or “sea” of electrons is what makes metals good conductors of electricity.
Another reason is that metals have a high number of free atoms or valence electrons. These free valence electrons are channeled through a matrix formed by the bonds, instead of moving randomly within the metal. This organized movement causes electric conductivity.