Okay kiddo, back in medieval times - which was a VERY long time ago - people didn't have the same kind of tools and machines that we have now. They had to use their hands and some pretty basic machines to get things done.
For example, instead of using a big truck to move heavy things, they would use something called a pulley. A pulley is like a little wheel with a rope wrapped around it. When you pull on the rope, the wheel turns and helps you lift things that are too heavy to lift on your own.
They also had something called a windmill. A windmill is a big machine with a bunch of long blades that spin around when the wind blows. People used windmills to grind wheat into flour or pump water from underground.
If you wanted to build a house, you couldn't just go to Home Depot and buy all the parts. You had to make them yourself! They used saws and hammers to cut and shape wood into the right shapes and sizes. And instead of using nails like we do now, they used something called a mortise and tenon joint, which is a fancy way of saying that they cut notches out of the wood pieces and wedged them together so they wouldn't fall apart.
Overall, people back then had to be very clever and resourceful to get things done without all the fancy technology we have now.