A common misconception is that Puerto Rico has a president. It does not. As a U.S. territory, Puerto Rico's head of government is the Governor, elected by the people of Puerto Rico every four years.
As of January 2, 2021, Pedro Pierluisi serves as Governor, succeeding Ricardo Rosselló (who resigned in 2019) and Wanda Vázquez Garced. The Governor leads the executive branch, appoints cabinet secretaries (with Senate confirmation), and represents the island in federal and international matters within the constraints of territorial status.
The confusion may stem from Puerto Rico's title—"Commonwealth" (Estado Libre Asociado)—or its high degree of internal autonomy. However, the ultimate sovereign authority rests with the U.S. Congress under the Territorial Clause of the U.S. Constitution. The U.S. President is the head of state for Puerto Rico, just as for the 50 states.