Action Points (AP) - determine how many actions a character can make during a combat turn. Different actions have varying action cost. (AP = DEX + 2)
Max AP
The maximum amount of action points per turn. If Max AP is 8, then even if you have 12AP, while you're wearing this armor your effective AP each round is 8.
AP Determination
source: https://rpgcodex.net/forums/threads/eyestabbers-in-depth-guide-to-dr-aod-mechanics.111868/