It's derived from the ways it's used in language. ie. first person is 'I did this', second person is 'you did this', third person is 'he/she did this'.
In games, you're either seeing it through the playable character's eyes (so it's first person, as the character is 'I') or you can see the person (in which they're a 'he/she' you're viewing).
A second person equivalent would probably be something like where the main character in the game is actually you yourself.














