What does electrical conductor mean?

Metals conduct electricity because electrons are free to move under the influence of an electric field. In liquid solutions, there have to be charge carriers, typically ions (molecules which exist in solution as ionized species) which can move under the influence of an electric field. In electro-plating baths, Cu ions move thru the bath and, when they arrive at the cathode, they pick up an electron from the cathode and are converted into metallic Cu (which "plates" out on the cathode as metal). hope this helps