Just means he gets an upgraded card released in packs (you can trade the cards with other players and play matches with them) for a limited period of time due to his performance in real life. Only 2 Brighton players have achieved it this year so it's a pretty good achievement :)
For his 2-goal performance against Charlton at the weekend, Dunk has been included in the FIFA team of the week this week, giving him an in-form card on ultimate team -
These are his stats -
He will be in FUT packs from 6:00PM