What does Exodus 10:18 mean?

This refers to Moses, who has just left Egypt's king. That king—the pharaoh—begged for an end to a catastrophic plague of locusts (Exodus 10:14–17). The catastrophe came because Pharaoh refused to release the Israelites (Exodus 10:3) who had been enslaved (Exodus 1:11–14). This is the fourth time the king has been forced to turn to Moses in humility, asking for relief (Exodus 8:8, 28; 9:28).

The overall emphasis of this series of events is the power of the Lord. His name, Yahweh (Exodus 3:15), is typically presented in English using small capitals as "Lord." That word appears fifteen times in connection to this plague, alone. God predicted the plague (Exodus 10:4–6), brought it (Exodus 10:13), and He alone could end it.

As with prior disasters, Pharaoh's mind will change (Exodus 8:15, 31–32; 9:34–35) as soon as the locusts are gone (Exodus 10:19–20). After so many choices to defy God, Pharaoh is now being used as an example of judgment (Exodus 4:21). The stubbornness now comes by God's choice, not Pharaoh's, and is meant to further prove the power of the God of Israel (Exodus 10:1–2).