What does Exodus 3:19 mean?

After commanding Moses and the elders of Israel to confront Pharaoh, God warns him that Pharaoh, the king of Egypt, will not be receptive. Pharaoh is also often called "king of Egypt" in Exodus, or "Pharaoh king of Egypt." According to God, the only way Pharaoh will agree to even the slightest release for Israel is if "compelled by a mighty hand." Moses will later refer to God as the one who brought the people from Egypt with a mighty hand (Exodus 32:11). The "mighty hand" of God is also mentioned nine times in Deuteronomy (Deuteronomy 3:24; 4:34; 5:15; 6:21; 7:8, 19; 9:26; 11:2; 26:8) and seventeen times total in the Bible.

This mighty hand of God will include ten plagues, culminating in the death of the firstborn sons of Egypt. Verse 20 predicts that "…after that [Pharaoh] will let you go." Further, the upcoming passage will conclude with the predictions the Jews will "plunder" the Egyptians through the items they request (Exodus 3:21–22). This prediction will be fulfilled in Exodus 12:35–36 as the fleeing Jews will be given jewelry and clothing by the Egyptians.