One of your units gets "Pay 0 Force Protect 2" for this attack. Play only when one of your other units in the same arena is being attacked.
Enhance: Pay 2 Force Also, that Protect ability may be used twice for this attack.
Keywords
Enhance
Enhance: [Effect]: A selective, static effect that means, "You may play the following effect by paying the additional cost." The effect states whether you play it "instead" or "also". You must declare it to get its effect.
Protect
Protect X: A layered ability activated during the damage prevention POP that means, "Prevent up to X damage to one of your other units in this arena." You can play Protect only once for each instance of damage. You don't have to use all of the Protect. You choose how much damage to Protect up to X, even if the full amount of damage or more is pending.