Debt-trap diplomacy is when a country offers another country a loan to help them with something like building a hospital or buying food for their people. But then the country that loaned the money sets up special rules so that the other country cannot pay the money back. This traps the other country into owing money that they can never pay back, and the country that loaned the money can then use that to control the other country. It's like a grown-up version of when your parents give you a loan, but then never let you pay them back.