The function of the large intestine in the human digestive system is primarily to absorb water and electrolytes from undigested food, thereby forming solid waste. It also plays a role in fermenting indigestible food materials, which can contribute to the production of certain vitamins, like vitamin K. The large intestine comprises various segments, including the cecum, colon, and rectum, and is crucial for maintaining fluid balance and eliminating waste from the body.