What does Bruno's and Gretel's tutor teach them?

It is implied that father is a respected leader and the former leader of the camp has been replaced or killed. Now, at Out-With, Bruno watches his Father standing in a circle of men outside his new home office. Bruno overhears them talking poorly of the former commandant. Father silences them and reminds them that they will have a new beginning tomorrow, with him as their leader. As they leave, they salute him and shout out "the two words that Bruno had been taught to say whenever anyone said it to him" (44).