The voltage is the working ability of the electric field. Its symbol is U, its unit is Volt (V). The electric current determines the value of electrons flooding in the leading material. Its symbol is I, its unit is Ampere (A). The electric resistance tries to block the flooding of electrons within the leading material. Its symbol is R, its unit is Ohm (Ω). The Ohm’s law
determines the context between this three value, the picture below makes easy to understand this relation. The voltage tries to push the electrons trough the wire and the resistance tries to avoid it.