The King has returned from hunting. Tréville asks if it had been successful. The word "halali" is mentioned.
The etiquette of royal hunting is very complex. Here is a site that describes some of it.

I am reminded of the Texan who was invited to participate in a foxhunt. His host was obliged to inform him afterwards that when he saw the fox, it was bad form to cry:"There goes the little red-assed bastard". The proper cry was: "Tallyho!"