Volt does not measure the number of electrons. It is their potential.
This analogy was taught to me by one of my greatest teachers.
Consider electricity as water, according to ohm’s law.
The voltage is the pressure within a waterline. It indicates how strong it is able to reach the other side.
Water is the charge (coulomb). It represents the number of electrons that want the other side.
Peter Harris has corrected the flow through the waterline as the current. This is how much charge actually passes through the waterline in a given time (coulombs per sec).
The last is resistance. The faucet is located at the end of the waterline. The faucet can be opened or closed depending on how much water (or electricity) is flowing through it. A faucet that is fully open is similar to a short-circuit.
We hope this helps!