I will give the old-fashioned version of this saga,
in which one picks either VOLTS or COULOMBS
as the "fundamental" unit and derives the rest from that.
Today the AMPERE [A] is actually the most basic unit;
it is defined to be the current required to flow
in both of two "very long" parallel wires
1 m apart
in order to give a magnetic force per unit length
of exactly
N/m acting on each wire.
No, I'm not kidding. Then the COULOMB [C] is defined
as the electric charge that flows past any point in 1 s
when a steady current of 1 A is maintained in a wire.
I.e. we have 1 C = 1 A-s.
Anyway, I will start with COULOMBS because it is more mnemonic.