A conversation has two sides
Talk keeps the transcript and translation together so you can follow who said what. Ask a short question, let the other person respond and take the next turn. It is designed for a shared exchange on one iPhone.
Voice & Talk · Premium
The person who knows the way is right in front of you. Choose a language for each of you, take turns speaking and use Talk to follow the exchange. A few words can open up the rest of your day.
Included in Premium on supported iPhones. Both languages need compatible on-device speech resources.

Talk keeps the transcript and translation together so you can follow who said what. Ask a short question, let the other person respond and take the next turn. It is designed for a shared exchange on one iPhone.
Use the microphone in Translate to turn your speech into text, then translate it. It is useful for a sentence you know how to say but would rather not type. Choose the source language first and check the transcript before relying on the result.
Speak one at a time and keep the phone close enough to hear. Short, complete sentences give the exchange a clearer shape. Read back an unexpected result or ask again; a noisy street or an unfamiliar name can trip up speech recognition.
A little preparation
While connected, select both Talk languages and check each language’s readiness. Complete the required translator and speech downloads, and make sure compatible voices are installed. Then try one short exchange with the connection off before your trip.
Open Talk, select one language for each person and allow the microphone and speech permissions when prompted.
Speak a short sentence, follow its transcript and translation, then give the other person a turn. Try this once offline before your trip.