The true statement about Francisco Pizarro is:
He executed Inca emperor Atahualpa.
Pizarro is best known for his conquest of the Inca Empire in present-day Peru and for capturing and executing Atahualpa, the last Inca emperor. The other statements are incorrect as they pertain to Hernán Cortés (who conquered the Aztecs) and the Maya civilization, which was not a target of Pizarro's conquests.