Okay, imagine you are playing a game and someone offers to sell you a special toy. You really want it, but you don't have enough money to buy it. So you make a deal with the person - you promise to pay them later, and in exchange they give you the toy now.
In Jeremiah 32, something similar is happening. There's a man named Jeremiah, who is speaking for God. God tells him to buy a piece of land even though the land is surrounded by enemy armies and is not worth much money. So Jeremiah goes to his cousin and offers to buy the land from him.
But there's a problem - the cousin thinks Jeremiah is crazy for wanting to buy this land, since it's not worth anything and they are in the middle of a war. So Jeremiah makes a deal with his cousin. He promises to pay him money for the land, but he also promises that God will take care of him and his family. Jeremiah knows this might seem strange, but he trusts in God's plan.
The story shows us that sometimes we might not understand why God wants us to do something, or why something seems crazy. But if we trust in God and follow His plan, He will take care of us and make sure everything works out in the end.