The statement that accurately describes Portugal's role in the age of exploration is:
"Portugal explored the coast of Africa, discovering a sea route to India and beginning the Atlantic slave trade."
During the Age of Exploration, Portugal was instrumental in navigating the coast of Africa and establishing trade routes to India, notably through explorers like Vasco da Gama. They were also among the first to engage in the Atlantic slave trade, which began in conjunction with their exploration activities. The other statements are not accurate regarding Portugal's explorations.