What does 2 Samuel 5:24 mean?

God said, 'When you hear the sound of marching in the tops of the balsam trees, move quickly. That means I've gone ahead of you to strike down the Philistine army.' 2 Samuel 5:24 - Modern Text Bible

(God gives David a sign—when he hears what sounds like an army moving in the trees, that's God leading the charge. David is to follow God's timing, not his own.)