What does 2 Samuel 18:20 mean?

But Joab told him, 'You're not the one to bring the news today. You can do it another time, but not today, because the king's son is dead.' 2 Samuel 18:20 - Modern Text Bible

(Joab knows the news is complicated—it's not just victory, but also the death of David's son. He doesn't want Ahimaaz to be the bearer of such painful news.)