Each of your adventurers has 4 attributes, which get higher with each level they gain:
Agl stands for Agility, and determines if you are quick enough to hit opponents, and evade attacks on yourself.
Atk is the strength of your Attack: when you make a hit, this one sets the damage it makes.
Def is your Defensive power, and will reduce the damage done by hits on you.
Hp are your Hit Points, or the amount of damage you can take. Once this reaches 0, the adventurer is out of the game. No worries though, the next run your adventurers will have brand new Hit Points to play with!