What does 2 Kings 18:26 mean?

Then Eliakim, Shebna, and Joah said to the field commander, 'Please speak to us in Aramaic, since we understand it. Don’t speak in Hebrew where everyone on the wall can hear.' 2 Kings 18:26 - Modern Text Bible

(Hezekiah’s officials try to keep the conversation private, worried about the morale of the people listening.)