Okay kiddo, a roadstead is like a special place in the sea where big boats can park and be safe from the waves and the wind. It's like a giant parking lot for ships.
Imagine you're playing with toy boats in a bathtub. When you make waves with your hands or blow on the boats, they move around and might tip over or crash into each other. But if you put your hand in the water to block the waves, the boats can stay still and safe. That's kind of what a roadstead does for big boats.
A roadstead is usually found near a coast, but far enough from the shore where the water is deep enough for big boats to park without hitting the bottom. There are often big rocks or cliffs around the roadstead to help protect the boats from the wind and waves.
Sailors really like roadsteads because they make it easier to load and unload things from the boat, like cargo or passengers. So, it's a pretty cool thing for boats and sailors!