In order to understand what 1 volt is, we have to first see what is a “volt” used for!
The volt - or V - is the SI unit for potential difference, which is defined as the amount of work done per unit charge needed to move a charge across two points of a conductor or circuit. In that regard, 1 volt is then defined as 1 J of work done for every 1 C charge as a charge passes through two points of a conductor.
Since:V = WQ
Therefore: 1 V = 1 J1 C
You may be wondering where this “work” is being done - think of it this way: the charge, while passing through two points of a conductor, has to put in some effort when pushing through. This “effort” translates into energy that’s being dumped across the circuit/conductor section for every charge. Hence, 1 J of work done for every 1 C charge!