The primary role of the colon in digestion is to absorb water and electrolytes from indigestible food matter, turning it into feces for elimination. It is responsible for completing the digestive process that begins in the stomach and continues in the small intestine. The colon also houses beneficial gut bacteria that play roles in synthesizing certain vitamins and fermenting unabsorbed material. Overall, the colon's activities are crucial for maintaining fluid balance in the body and ensuring the efficient removal of waste products.