Why Current is the rate of flow of electric charge past a point in a circuit, and its unit is the ampere (amp), equal to one coulomb of charge per second. The other three units measure different quantities: volts measure electrical pressure (EMF), ohms measure resistance, and watts measure power. In Ohm's Law, I = E/R, the I term is always in amperes.
Watch out Volts is the common trap because voltage and current are often mentioned together, but volts measure the electrical force that pushes current, not the flow itself.
Amperes = Amount of charge flowing. Volts push, ohms resist, watts work, amps flow.