In Final Fantasy 7 you are a young warrior Named Cloud.  You must go on a journey to defeat the evil seperoth.  

This warrior right here is cloud.  He is the main character of this game.  He can learn limit breaks.  Limit breaks are super attacks used to defeat the enemies.  Cloud has people join him to defeat the evil seperoth.  This seperoth has an evil mom jenova.  Cloud must defeat these people once and for all.

This is Cid.  He joins cloud on his quest.  There isn't much background about this guy.

This is Tifa.  One of clouds best friends.  They help each other out in defeating the evil villains.  They make an awesome team if you can level them up a lot.