What does the separation of powers between the three branches of your government means?

There is a system of checks and balances. All the authority for the government is enumerated or eliminated by what is in the Constitution. The Legislative branch (House of representatives and Senate) makes the laws; the Executive breach (headed by the President) executes and enforces the laws; the Judiciary branch (headed by the Supreme Court) rules on case if crimes and civil disputes, and rules on whether some laws, or their applications violate the Constitution. Each of the three branches are affected by actions of the other two.