The Reformation was a movement during the 1500s that ultimately led to a separation from the Catholic Church and the creation of hundreds of new sects and eventually denominations of Christian churches. It's called the Protestant Reformation because it was started by disgruntled Christians who protested many aspects of the Catholic Church including doctrines and practices. Martin Luther is credited most with exposing problems with the Catholic Church through several published works that spread like wildfire thanks to the newly invented printing press. He originally only wanted to reform certain things in the Catholic Church like the practice of indulgences rather than break away from the Church, but after being excommunicated and seeing no promising chances for change, he decided to start his own church, which later became known as the Lutheran Church. Today most "Protestant" churches include most Christian churches that are not either Catholic or Orthodox.
The Age of Exploration began a little before the Reformation, but continued well after Luther's life. Due to the breakthroughs in scientific discovery, a new era had begun where people used the scientific method to explain the natural world. Known as the Scientific Revolution, beginning around the mid 1400s, all kinds of new inventions were changing life in Europe. Improvements to large ships and navigation instruments allowed Portuguese sailers to explore the west coast of Africa and take advantage of trading opportunities. Soon other European nations were following their lead and finding better trade routes to Asia and looking for new land to exploit. Enter Christopher Columbus sailing for Spain and claiming land for King Ferdinand and Queen Isabella in 1492 and the Age of Exploration was off and running changing the world forever.