Complex sentence: He began his study of Nahuatl while traveling across the Atlantic, learning from indigenous nobles who were returning to the New World from Spain, and would later be recognized as one of the Spaniards most proficient in this language.
Split into simpler sentences: He began his study of Nahuatl while traveling across the Atlantic, learning from indigenous nobles who were returning to the New World from Spain. Later he was recognized as one of the Spaniards most proficient in this language.