Ferdinand Magellan did not actually prove that the world is round. The concept of a spherical Earth was well-established and widely accepted by Magellan's time in the 16th century. The ancient Greeks, such as Pythagoras and later Aristotle, provided evidence and arguments for a spherical Earth based on observations and logical reasoning.
Magellan's significant contribution to world exploration was his circumnavigation of the Earth, which demonstrated the possibility of traveling around the world by sea. In 1519, Magellan set sail from Spain with a fleet of ships, and his expedition became the first known voyage to complete a circumnavigation of the Earth.
During the journey, Magellan's ships traveled westward, crossing the Atlantic Ocean and entering the Pacific Ocean via the Strait of Magellan, which was named after him. They continued their voyage across the Pacific, eventually reaching the Philippines. Unfortunately, Magellan was killed during a battle in the Philippines, but one of his ships, the Victoria, continued the journey back to Spain, completing the circumnavigation.
Magellan's expedition provided practical evidence that it was possible to sail around the world, supporting the existing understanding that the Earth was a sphere. It further dispelled the notion that the Earth was flat, which had been largely rejected by scholars and navigators long before Magellan's time.