Obviously, there had to be a translator for the two peoples. Who would learn the language of the other civilization? How would they go about learning the language? Would they live peacefully among their opposition to study the language? Or would they learn from a distance, like from books or texts?
The translators in the early Spanish colonization were usually hostages. Dona Marina was a slave that was given to Cortes, baptized and 'educated,' she ended up being Cortes' mistress.
Gerónimo de Aguilar was a priest who survived a shipwreck and was taken as a Mayan slave and he learned the language that way. Cortes heard about the strange looking man and with assistance from Malinche he was brought to Cortes.
The Franciscans also set up schools for the children after the conquest where they were taught Spanish and translated some of the Mayan texts.