Final answer:
The preposition 'para' is used to indicate a destination in Spanish.
Step-by-step explanation:
The phrase 'Yo salgo para Nueva York mañana' translates to 'I am leaving for New York tomorrow.' The preposition 'para' in this context is used to indicate a destination. It shows that the speaker is going to New York as their intended destination.
Learn more about Prepositions in Spanish