What does Psalm 33:17 mean?

Israel needed to understand that it is futile to rely on a war horse for deliverance in battle. No earthly object or advantage is enough, by itself, to guarantee victory. Ultimately, victory belongs to the Lord God.

In the era of the Exodus, Egyptian cavalry was extremely powerful (Exodus 12:37–39; 14:5–9). The Hebrews were just-liberated slaves ill-equipped for battle. Nevertheless, that difference in strength was not what mattered. War horses and well-built chariots were not enough to defeat the power of God. When the final encounter was over, the Egyptian cavalry was dead and the Hebrews were unhurt. What made the difference? Exodus 14:24 explains how God terrified the pursuing Egyptian cavalry, terrifying them as they tried to chase Israel across the Red Sea (Exodus 14:21–23). Before long, the potent Egyptian army was drowned in the Red Sea (Exodus 14:26–28).