Ari yells at someone for taking the dealer's break card.
In simple blackjack strategy, you would assume that the next card in the deck is ten points since there are more cards with said points (10,J,Q,K). If the dealer is showing a 2-6, simple play would be to stand and hope the deal busts on the upcoming ten (hopefully).
In the situation in the episode, the other player decided to split K's, and used up the next two tens in the deck, thus "burning the break card."
Note: It later turns out, the dealer had 11. Therefore, the break card would have actually given the dealer 21. A rare time that splitting K's pays off.