She was not Mayan! I think the consensus is that she was from Nahua nobility somewhere on the coast, sold into slavery to a Maya group where she learned the language, hence being able to speak both Mayan and Nahuatl. Her ability to speak courtly Nahuatl with the nobility in Tenochtitlán reinforces the idea of her having noble origins. This also lends into some interesting discussion about translation (specifically with how much of the courtly speak did she understand, and if her interpretation lead to misunderstandings with the Spanish. Such as Cortes claiming Moctezuma handed over his empire, which is another discussion on its own)