Supply chain sustainability means ensuring that the things we buy are made in a way that doesn't harm people or the environment.
Let's say you want to buy a toy. The toy store buys the toy from a company, which gets the plastic and other materials from suppliers. All of these people and companies are part of the "supply chain."
If the toy is made using materials that damage the environment or people who made them, that's not sustainable. If the toy is made in a factory that pollutes the air, that's not sustainable either.
To make the supply chain sustainable, everyone involved has to work together to make sure the materials are sourced responsibly, factories are safe for workers, and everything is done in a way that doesn't harm the environment.
This way, when you buy a toy, you can be sure that it was made in a way that is good for people, the planet, and for future generations too.