Canned green beans are already cooked during the canning process, so technically, you don't have to cook them again. However, many people prefer to heat them before serving to enhance their flavor and texture. Heating canned green beans can be done quickly and easily on the stovetop, in the microwave, or even in the oven. These methods help to warm them up and make them more enjoyable to eat. Additionally, adding seasonings or other ingredients while heating can further enhance their taste.