Okay kiddo, so have you ever seen a toy train set? A decauville wagon is like a tiny train car that can be used to carry things around. Just like you might use a toy truck to carry your toys from one room to another, decauville wagons can carry all kinds of things like rocks, dirt, or even other toys!
But, here's the cool part: decauville wagons can be connected together to make a longer train, just like how train cars connect to each other in real life. This means that people can move lots of things at once, making their work easier.
Decauville wagons were used a long time ago in factories, mines, and other places where people needed to move heavy things around. They were named after the person who invented them, Paul Decauville, over 100 years ago!