Christopher Columbus' voyages to America changed Spain in several ways. Most prominently, the New World afforded Spain with vast amounts of wealth from agricultural plantations and gold and silver mines. This wealth allowed Spain to increase its military spending dramatically, thus rendering Spain the most powerful nation in Europe. Spain even assembled a large navy--the Spanish Armada--to attempt an invasion of England (unfortunately for Spain, this invasion failed for a variety of reasons).
Columbus' voyages also afforded the Spanish people with a "land of opportunity." Sons of nobility, who--because they had older brothers--would not receive large inheritances, had the opportunity to become conquistadors (Spanish explorers and warriors) and make their mark--and fortune--in the New World.
Finally, Columbus' voyages helped spark the "Age of Discovery," both in Spain and throughout Europe. His discoveries helped "broaden the horizons" of the Spanish people by showing them there was more to the world than they were aware. These faraway lands and their mysterious inhabitants captured the imaginations of Spanish citizens.