Relative motion means a motion relative to a reference point. We can also say, relative motion means motion referred or observed from a reference point.
For example, Alex is in a train and Ace is at the station, when the train starts moving, for Ace it is moving at a speed of 10 m/s, but for Alex it is moving at 0 m/s, or we can say that it is at rest for Alex, but in motion for Ace. This is relative motion.
The ampere (A) is a basic SI unit consisting of the amount of electric charge or number of electrons that pass a point in a electrical circuit in one second. The volt (V) is the electrical potential causing electrons to move through a wire. It is a joule of energy per coulomb of charge.