Juice is a drink that's made from fruit, like orange juice or grape juice. Juice also refers to the liquid drippings of cooked meat and other food.
Some people like apple juice, while others prefer tomato juice. A much less appetizing — but necessary — type of juice is the fluid in our bodies, like digestive juices that help break down food in your stomach. Informally, you might refer to your creative strength as juice, and also use the word to mean electrical energy: "The batteries in my flashlight are out of juice."