The main roles of the executive branch in the U.S. government include enforcing laws, conducting foreign affairs, and overseeing federal agencies. The President, as the head of the executive branch, has the authority to implement policies and ensure that legislation passed by Congress is enacted effectively. This branch also plays a crucial role in national security, making decisions on defense and foreign policy. Additionally, the executive branch is responsible for issuing executive orders to direct government operations and can propose budgets to Congress. Overall, it acts as the administrative backbone of the federal government.