Answer:its basically the three branches of government and all of the branches need to approve of a law the legislative, the executive and the Judaical branches without it one branch could make a law and it wouldn't be fair to the people here is an example
lets say the executive branch makes a law that says that the poor have to pay a WAYYY higher tax then the rich and the other branches had no say in that and wouldn't have a way to stop that because the executive branch made it impossible to stop them because of other laws they made this could even lead to a civil war.
hope that this helps <3