The role of the kidneys in the body is to filter and remove waste products from the blood, regulating the body's fluid and electrolyte balance. The kidneys maintain homeostasis by adjusting the excretion of water, sodium, potassium, and other substances based on the body's needs. They also play a crucial role in producing hormones, such as erythropoietin, which stimulates red blood cell production, and they regulate blood pressure through the renin-angiotensin system. By maintaining proper kidney function, the body can effectively manage waste and ensure overall health.