A tong is like a club that people can join. It's usually made up of people who have similar backgrounds or interests. You might join a tong because your family is part of it, or because your friends are in it.
Tongs started a long time ago in China, where people would form groups to help each other out. They might have helped each other find work, or protected each other if there was trouble in the neighborhood. When Chinese people came to other countries, they started forming tongs there too.
Today, tongs are still around and they can do many different things. Some tongs might help people who are new to a country, by showing them around and helping them find things they need. Other tongs might get together to celebrate holidays or host events. Some tongs might also work to improve their community by volunteering or donating to charity.
No matter what the tong does, it's a way for people to come together and support each other. Think of it like being part of a team where everyone works together to make good things happen.