A horse-drawn boat is a big boat that is pulled by a horse. Have you ever seen a carriage or a cart being pulled by a horse? It's like that, but instead of carrying people or things on land, it carries people or things on water!
The boat has a special path made just for it, and the path is called a canal. A canal is like a big ditch dug into the ground that is filled with water. The boat sits in the canal, and a horse is hooked up to the boat with a rope.
The horse then walks along the path next to the canal, pulling the boat along with it. There are people in the boat who steer it along the canal using ropes and big poles.
It's kind of like going on a really slow boat ride, but it's also like going on a really slow horse ride too! Horse-drawn boats were used a long time ago when people needed to transport things like coal or goods from one place to another.
Nowadays, you can still see horse-drawn boats in some places as a fun way for people to take a ride and learn about history.