Nope. AirPods need to be in an ear or in something fooling it is in an ear to be active. Place on a counter and they are off.
Also it is very difficult to follow difficult to follow a conversation between two people speaking a foreign language to each other. A brief pause and it will stop listening and start repeating what is said. If there is no pause than its hard to tell who is saying what.
Translate is also supposed to be used from the phone because it will pipe the audio into the ear piece. So when legitimately used the foreign speaker doesn't get what you are saying translated to their native language.
AirPod do work good for secretly translating though. If you are getting a pedicure, at a restaurant etc etc using the AirPod works good though. Word of warning though you may not want to know what people are saying.
I could translate half the conversation between two Vietnamese women when I was getting a pedicure (for an Indian friends wedding). They were wondering if I was married, noticed I didn't have a ring and after some random stuff and stuff I don't think translated properly finally decided that I was a homosexual. I'm not nor does that offend me but I could see it being a problem for certain people in certain situations.