AMERICA is a continent not a single country. Understand geography.
It is also called the New World, which are the combined continental landmass of the North America and South America continents in the Western Hemisphere. America covers 8.3% of the Earth's total surface area (28.4% of its land area.
Humans first settled America from Asia between 40,000 BCE and 15,000 BCE.
The first European discovery of and settlement in the Americas was by the Norse explorer Leif Ericson. However the colonization never became permanent and was later abandoned.
Then Christopher Columbus from 1492 to 1502 resulted in permanent contact with European (and subsequently, other Old World) powers, which led to the Colombian exchange. Diseases introduced from Europe and Africa devastated the Indigenous peoples, and the European powers colonized America.