The Basel Convention is a set of rules agreed upon by countries around the world to help protect the environment from hazardous waste.
Imagine you have a toy that you don't want anymore. You could throw it away in the garbage, but if that toy has batteries or chemicals inside it, it could be very harmful to the environment. The same goes for large companies that have waste with chemicals and other dangerous substances.
So, the Basel Convention sets up ways for countries to properly dispose of hazardous waste, like these toys with batteries or chemicals. It also stops companies from shipping their hazardous waste to other countries that might not have the same rules about how to dispose of it. This way, we can protect people and the environment from harm.