"Cơm rượu" is a very special type of rice that is used in Vietnam to make a type of alcoholic drink called "rice wine". The rice is cooked and then mixed with yeast and a little water. The mixture is then left for a few days to ferment, which means that the yeast turns the sugar in the rice into alcohol.
After about a week, the mixture is strained to remove the solid bits, leaving behind a clear liquid which is the rice wine. This wine is usually quite strong, and tastes a bit sweet and sour.
Sometimes, people also add fruits or other herbs to give the rice wine a different flavor. In Vietnam, "cơm rượu" is often served at special occasions, such as weddings or festivals, and is a symbol of hospitality and celebration. However, it's important to remember that even though it's called "rice wine", it's still an alcoholic beverage, so only adults should try it and always drink responsibly.