Ah, thank you for the question. That is for player facing rules about dodging or defense. If a creature has AC/ATK (12), it means to hit IT, you need to roll 12 or better. For you to dodge ITS attack, you need to roll that. It could be the creatures COMBAT score, basically, but was trying to use the typical game parlance. Because you are playing solo, the monster doesnt roll to hit you, you roll to avoid the monster.