Imagine you have a bowl of rice, but the rice is still covered in a hard shell or husk. The husk is not good to eat, so you need to remove it in order to get to the yummy rice inside.
A rice pounder is a special tool that people use to remove the husk from rice. It looks like a big stick or mallet, and it is used to hit the rice. The rice is put in a special container or mortar, and then the pounder is used to hit it over and over again until the husk breaks off.
It might sound like hard work, but it actually used to be a very common way of processing rice all over the world, especially in places like Asia and Africa. Nowadays, people mostly use machines to remove the husk from rice, but traditional rice pounders are still used in some places for cultural or religious reasons.
In summary, a rice pounder is a tool that people use to remove the shell or husk from rice by hitting it with a big stick or mallet. It used to be a common way of processing rice, but now it is mostly done by machines.