A ring saw is a special tool that is used to cut through things like stone, glass, or tile. It looks kind of like a small circular saw, but instead of a round blade, it has a long, skinny blade that is shaped like a loop or a ring.
When you turn on the ring saw, the blade spins around really fast, and you use it to slowly cut through the material you're working with. Imagine using a pencil to draw a line on a piece of paper, but instead of leaving a mark behind, the ring saw blade cuts a thin line through the stone or other hard material.
Ring saws are used by people who do things like make mosaics or stained glass windows, or who work with stone to make sculptures or other art. They are very powerful tools, so it's important to be careful when using one and to wear things like safety goggles and gloves to protect yourself.