Hernan Cortez was a Spanish conquistador (a Spanish soldier or conqueror). He was an explorer and traversed through modern day Latin America. He landed in Mexico in 1518, and conquered the Aztec empire in 1521.
Francisco Pizarro was another Spanish conquistador. He conquered the Incan empire in 1533. In 1533, he founded the city of Lima in modern day Peru.
Ferdinand Magellan was a Portuguese explorer who started a voyage to sail around the world with his crew in 1519. Ferdinand died in 1521 before the rest of his crew completed the voyage in 1522.
The conquistadors had a large advantage over the natives of North and South Americans. They had muskets, canons, and warships while the natives had bow and arrows, and spears. The Spaniards brought diseases with them which killed off thousands of the natives.
The conquistadors' steel armor was impenetrable to the natives' primitive weapons.