V or v is the twenty-second letter of the Latin Alphabet. (The English Language, and many other languages, usually uses the Latin Alphabet, when being written.)
The letter V is usually pronounced: Vee. Or less frequently as: Ve.
The letter before V is: U. The letter after V is: W.
V or v is also the Roman Numeral for Five (5).
The Roman Numeral before V is either written as IV or IIII. The Roman Numeral after V is: VI.
In Chemistry, V is the Chemical Symbol for Vanadium.
In Physics, V is used as a short form for both Volt or Voltage. (Note that Volts and Voltage, though related, are different things, despite sounding similar.)
For example, in Ohm's Law, we have V (for voltage) being used as....
V = I × R
Or in other words, the Voltage equals the Electrical Current times the Electrical Resistance.
Also, V (for volt) is used to represent the a unit of measurement used for voltage, called the volt. As in....
Which reads, "Nine Volts".
Also, v is sometimes used as an abbreviation for Versus (as an alternative to vs). As in....
Hulk Hogan v Jesse "The Body" Ventura
Which reads, Hulk Hogan versus Jesse "The Body" Ventura.