Legislation refers to any law enacted by the governing body of a state or nation. In the United States, both the House of Representatives and the Senate must pass a bill (by majority approval) in order for the bill to reach the President’s desk.
If the President signs a bill, it becomes law. If the President vetoes (or, during the last 10 days of a legislative session, simply does not sign) the bill, it returns to the chamber from which it originated.
The Congress can override the President’s veto with a two-thirds majority in both chambers. Legislation can also be adopted by a state or local legislative body, through a similar process. The courts have the power through judicial review to interpret what the legislation means when the clear language of the statute is not determinative and to declare that legislation is unconstitutional.