

Every RPG has to have stats. In case you somehow don't know, they're the characters' performance put into numbers.
HP
HP, or Health Points, is the characters' health. Each time a character is hit, they will lose HP. If their HP hits 0, they will be unable to fight until the battle is over (where they will be left with 1 HP) or a reviving item is used. If every character loses all of their HP in battle, you lose the fight and have to start from where you last saved. Ouch. Make sure you heal often! Buy the right items so you don't have to suffer this cruel fate.
SP
SP, or Special Points, represents the characters' ability to use Specials. The more powerful a Special move is, the more SP it requires, and if that character doesn't have enough SP to use it, then he or she can't! Like HP, SP can be restored by using an inn or a restaurant, but you can't buy SP restoring items! Use every SP restoring item you find wisely!
ATTACK
The characters' physical attack stat. The higher this is, the more damage the character will be dealing using their basic attack weapon. Few Specials also use physical attack as well.
DEFENSE
The characters' physical defense stat. The higher this is, the less damage the character will be taking from physical attacks.
FOCUS
The characters' special attack stat. The higher this is, the better specials will work. This also helps increase the damage of some special moves.
GUARD
The characters' special defense stat. The higher this is, the less damage the character will be taking from special attacks. Don't forget that anything that comes in contact, such as punch or kick, is physical, while any projectile is special.
SPEED
How fast a character is. All of the characters and enemies have Speed, and whoever's Speed is the highest gets to make their move first. Obviously, the character or enemy with the lowest Speed goes last. Sometimes, there may even be randomness involved.