The answer that you are most likely supposed to give for this question is that Christopher Columbus represented Spain on the voyage in which he “discovered” the New World. Historians might disagree with this answer as it is not completely clear that Spain truly existed as a country at that point. The area that is now Spain had been divided into different kingdoms at least until Ferdinand and Isabella married, and many scholars feel that Castile (the kingdom over which Isabella reigned) and Aragon (Ferdinand’s kingdom) were essentially separate kingdoms even after the time when Columbus sailed.
At any rate, most people would say that Columbus sailed for Spain. He was Italian by birth, but the Spanish monarchs were the first sponsors he could find to fund his voyage.
Christopher Columbus represented Spain on his voyage. Columbus was looking for a different, shorter way to Asia. Traveling by land was difficult. Columbus thought there might be a shorter water route to Asia. Instead of going by water around Africa to Asia on a voyage that could be filled with danger because of bad weather, Columbus believed it might be easier to go to Asia by heading west. While some doubted that Columbus would be successful, the King and Queen of Spain were willing to take a chance on his voyage. Thus, they sponsored his voyage.
The King and Queen of Spain viewed his voyage as a way to gain fame and fortune. If Columbus was successful, they might be able to claim any minerals he discovered. They also might be able to spread their religion, Christianity, to other places. Columbus also could receive fame and riches if he was successful.
Of course, we know the Columbus didn’t find that shorter route to Asia. In fact, he wasn’t the first to find the Americas. However, he did lead four voyages for Spain to what we now call the Americas. The fortune he hoped to find never really materialized as a result of his voyages.