Complex sentence: The only single indigenous language spoken by more than a million people in Mexico is the Nahuatl languages; the other native American languages with a large population of native speakers include Quechua, Aymara and Guaraní and some Mayan languages.
Split into simpler sentences: The only single indigenous language spoken by more than a million people in Mexico is the Nahuatl languages. Nahuatl is one of the native American languages with a large population of native speakers, along with Quechua, Aymara and Guaraní and some Mayan languages.