'Service' in the Bible

young men in whom there was no physical defect and who were handsome, well versed in all kinds of wisdom, well educated and having keen insight, and who were capable of entering the king's royal service -- and to teach them the literature and language of the Babylonians.

So the king assigned them a daily ration from his royal delicacies and from the wine he himself drank. They were to be trained for the next three years. At the end of that time they were to enter the king's service.

When the king spoke with them, he did not find among the entire group anyone like Daniel, Hananiah, Mishael, or Azariah. So they entered the king's service.