The major significance of Vasco Da Gama's voyages was that they opened maritime trade between Asia and Europe and they helped to create a Portuguese empire.
Vasco Da Gama was the first European to sail around the continent of Africa to Asia. This allowed Portugal to start trading for spices in Asia. This was a hugely lucrative trade. Because it was such a rich trade it helped to make Portugal a major power even though Portugal was such a small country. In the years after Da Gama's voyage, Portugal became a world power to rival Spain. This would not have been possible without Da Gama's voyages.
Vasco Da Gama made Portugal a major player in the European spice trade during the late fifteenth and early sixteenth centuries. Da Gama established a trade route between Lisbon and Calcutta--he was the first European to do so. Using a sea route discovered by Bartholemeu Dias that went around the Cape of Good Hope, Da Gama gained riches for both himself and Portugal. Ultimately, Da Gama would die in India after his third voyage there. As a result of Da Gama's efforts, Portugal became a major spice exporter. This cut into the power of Venetian traders, who had long monopolized the trade in the Mediterranean. Without the need to cut through the Middle East in order to get to the lucrative spice trade of Asia, European nations soon focused their efforts on merchant ships. While Portugal would revert back to its status as a relatively poor nation, Da Gama's accomplishment made other European nations dream of trade empires.
Portugal was the first European nation to make an attempt at exploration. Exploration began with Bartholomeu Dias rounding the Cape of Good Hope off the African coast in 1488. Vasco da Gama rounded the cape and sailed on to India and returned to Portugal loaded down with spices. Because da Gama made so much money in profits from the spices he brought back it created interest in a growing spice trade. This was the beginning of the first European trading empire. Portugal conquered the island of Melaka which gave them a point in their trade with China, the Spice Islands and India.