You mean Dacote. Stop: +4 Dmg means that if your opponent plays a card with SoA (stop opp. ability), your card gets the +4 damage added, otherwise the ability isn't activated. Basically it's the opposite of a normal ability.
Normal ability: stopped by SoA
"Stop" ability: activated by SoA
SoA = Stop Opponent Ability.
If Dacote’s ability is cancelled by the opposing character, Dacote's damage is increased by 4.
You need to be facing a card with Stop Opp Ability as their Ability/Bonus. e.g. Jackie, Erika etc.
While facing them, Dacote's ability is activated and considering he has his Bonus on, he will have 12 Damage.