What are the three parts of the Monroe Doctrine? What do they say?

There are 4 points

Declaring that the Old World and New World had different systems and must remain distinct spheres, Monroe made four basic points: (1) the United States would not interfere in the internal affairs of or the wars between European powers; (2) the United States recognized and would not interfere with existing colonies and dependencies in the Western Hemisphere; (3) the Western Hemisphere was closed to future colonization; and (4) any attempt by a European power to oppress or control any nation in the Western Hemisphere would be viewed as a hostile act against the United States.

Explanation:

Monroe Doctrine, (December 2, 1823), cornerstone of U.S. foreign policy enunciated by Pres. James Monroe in his annual message to Congress.