Ok kiddo, have you ever worn a leather jacket or seen someone wearing one? Well, to make leather, they use the skin of animals like cows or pigs. But before we get a leather jacket, they have to do lots of things to the leather to make it strong and durable.
One way they used to do it a long time ago was by boiling the leather in water. They put the raw animal skin in a big pot of water and boiled it for a long time. This made the leather tough and gave it a hard texture.
After boiling, they would stretch the leather out and then let it dry. This made the leather stiff and able to hold its shape. Then they would cut it into pieces and use it to make things like shoes, belts, or even armor for knights.
Boiled leather was really popular back in the old days because it was cheap to make and very strong. But nowadays, people use different methods to make leather, so you don't see boiled leather as much anymore.
So, that's boiled leather for you, kiddo. It's just leather that's been boiled in water to make it strong and durable.