Soju is a type of alcoholic drink that comes from South Korea. It is made by taking a bunch of grains and fermenting them, which means letting them sit for a while so that they start to break down and turn into alcohol. Then, the fermented grains are distilled, which means they are heated up and the alcohol is separated from the other stuff in the mixture.
The end result is a clear and colorless liquid that is very strong - it usually has an alcohol content of around 20 to 24 percent, which means it has a lot more alcohol than beer or wine. Soju is often compared to vodka, which is another clear, strong, and colorless alcoholic drink.
People in South Korea love to drink soju - in fact, it is the most popular alcoholic drink in the country! You may have heard that when people drink soju, they often do it in a particular way: they'll pour some into a small glass, and then they'll pour some into a second glass. Then, they'll hold both glasses out in front of them and say "gunbae!" (which means "cheers" in Korean), before downing both glasses in one go.
Soju is a very important part of Korean culture - it is often drunk at social gatherings like dinners or parties, and some people even use it to make medicinal drinks that are supposed to help with things like digestion or a sore throat. But because soju is so strong, it's important to be careful when drinking it - always make sure you're drinking in a safe and responsible way.