The main importance of the checks and balances is that any action taken by one of the branches of government must go through the other two branches of government.
For example, in order to a bill to pass, it must be approved by Congress, signed by the President, and be seen as Constitutional by the Supreme Court.
Another example, the Supreme Court Justices, who control most of the judicial branch, must be appointed by the President, who is in the Executive branch. However,