According to the quote, what are the European powers prohibited to do in the American continents?

Although initially disregarded by the great powers of Europe, the Monroe Doctrine became a mainstay of U.S. foreign policy. In 1823 U.S. President James Monroe proclaimed the U.S. protector of the Western Hemisphere by forbidding European powers from colonizing additional territories in the Americas.

You don’t have to names or other options up here so idk dude