When Pharaoh refuses to release God’s people from slavery, most English translations say that “the Lord hardened Pharaoh’s heart, and he did not listen” to Moses’ demand for freedom (Exod 9:12). The Hebrew for “hardened” here is חזק (hazaq) and “heart” is לב (lev). When readers see that the Lord “hardened Pharaoh’s heart,” they might think of God forcing Pharaoh to act a certain way; it sounds like Pharaoh would let the Israelites go, but God stops him by overriding his autonomy.
However, rather than “harden,” hazaq literally means to “strengthen,” and along with “heart,” lev can also mean “desire” or “will.” Thus, an equally valid translation is that “the Lord strengthened Pharaoh’s will.” Do you see the difference here? For God to strengthen Pharaoh’s will does not mean that God forced him to do something against his will, but just the opposite: it was already Pharaoh’s will to keep the Israelites enslaved, so God strengthened the pharaonic will that was already there.
If you’ll forgive a somewhat crude analogy, there’s a well-known story of parents catching their teenager smoking. Instead of taking the cigarettes away, the parents say, “So you want to smoke cigarettes, do you? Well now we’re going to make you go through the entire pack!” The parental logic here is that the teenager would get so sick that he or she would never want another cigarette again!
While I don't recommend this method for parenting teenagers, it works as an analogy because this is essentially what God does to Pharaoh: God says, “So you refuse to let my people go? Ok, then I’m going to reinforce your stubborn will and watch you go through an entire pack of plagues.” The Lord doesn’t take away Pharaoh’s free will when he refuses to let the people go; rather, God reinforces or strengthens that will.