You slice something up by cutting flatpieces off if with a knife. When you are taking many slices off something, you try and make them all the same thickness.
Something is soaked if it is completely wet. Many foods require soaking before they can be cooked, or they will be hard in the middle even after they are cooked. Dried pulses like lentils and beans often need to be soaked overnight. The larger the bean the longer it will need soaking for.
Sorghum is a type of grass that is grown for its seeds for food and also for fiber to make things from. It is grown mainly in Africa, and is used both for human and animal food. It can be popped like popcorn and can be made into couscous.
Soup is a food that is made by cooking things like meat and vegetables in water with herbs and spices. Soup is usually very runny, and you have to eat it with a spoon not a knife and fork.
Soy sauce, also called soya sauce, is a sauce made from fermented soybeans, water and salt. Soy sauce has a distinctive savory flavor, and is an ingredient in many Asian dishes.