What does 2 Kings 18:27 mean?

But the field commander shot back, 'Do you think my master sent me to talk only to you and your king? No, this message is for everyone sitting on the wall—who, like you, will have to eat their own waste and drink their own urine during the siege.' 2 Kings 18:27 - Modern Text Bible

(The Assyrian spokesman wants everyone to hear his threats, aiming to terrify the people and break their will to resist.)