What does Exodus 10:27 mean?

Before Moses came back to Egypt, God indicated that he would make the Egyptian king stubborn (Exodus 4:21). But this did not happen immediately. Pharaoh was given multiple chances (Exodus 5:1; 7:16; 8:1, 21; 9:1, 13) confirmed with supernatural signs (Exodus 7:21; 8:6, 17, 24; 9:6, 10, 24; 10:14, 23) to obey the Lord's command to release the Israelite slaves. He has rejected these over and over (Exodus 5:2; 7:13–14, 22; 8:15, 19, 32; 9:7, 35). In those instances, Scripture indicates that Pharaoh's heart was "hard" or "hardened."

The same expression is used elsewhere in Scripture. It always indicates someone who resists God: a person who refuses to listen to His conviction and wisdom, such as Sihon of Heshbon (Deuteronomy 2:30), Nebuchadnezzar (2 Chronicles 36:13), Belshazzar (Daniel 5:20), Jesus' enemies (John 12:40), and at times even Jesus' disciples (Mark 6:52; 8:17). The Lord warned against the Jews hardening their hearts (Deuteronomy 15:7). Many of Israel's enemies hardened their hearts so they would be completely destroyed (Joshua 11:20). This is a recipe for disaster (Job 9:4; Proverbs 28:14).

Of course, in some of these incidents, the Bible notes that God was the one responsible for the obstinance: that He "hardened" people. This is part of God's power, and His right, to use His creations as He sees fit (Romans 9:18). Eventually, Pharaoh ran out of time to submit to God (Proverbs 29:1). When that moment came, God began using Pharaoh as a demonstration of divine wrath. This meant removing his ability to choose and condemning him to even more punishment (Exodus 10:1–2). Here, this means Pharaoh will angrily reject another opportunity to avoid disaster.