What does 1 Samuel 17:24 mean?

The Israelites are gathered for battle with the Philistines at the Valley of Elah (1 Samuel 17:1–3). Daily they form their battle lines and shout war cries (1 Samuel 17:20). But the Philistines have proposed champion warfare to determine this battle. One representative from each side would be sent to fight. The people of the man killed in that duel would become the servants of the people of the victor. The Philistines' champion is Goliath of Gath, an imposing man of enormous stature and equipped with body armor and advanced weaponry (1 Samuel 17:4–7). This champion taunts the Israelites twice-daily for forty days (1 Samuel 17:8–10, 16).

Goliath is apparently unbeatable. So, not surprisingly, the Israelites respond in fear (1 Samuel 17:11). Here we see that the Israelite soldiers are not simply afraid, but that the men actually flee from Goliath. Since Goliath is said to have "come up" to shout his challenge to them, it's possible that he even approached their battle line. Those nearest him, at least, retreated to be out of reach of his enormous spear.

In this way, one single Philistine melted the courage of Saul's entire army.