"Conversation Mode" is a new interface for Android Phones within Google Translate that’s optimized to allow you to communicate with a nearby person in another language.
In conversation mode, simply press the microphone for your language and start speaking. Google Translate will translate your speech and read the translation out loud. Your conversation partner can then respond in their language, and you’ll hear the translation spoken back to you. See an example below.
A new look for Google Translate for Android
Conversation Mode in Google Translate for Android