Is it ok to talk to my friend in a different language during a class Zoom meeting?
That depends. Why do you want to talk to them in a different language?
I want to have a secret conversation.
It is ok if you want to talk to your friend to your friend in another language in a private setting. However, these Zoom meetings are meant to be open discussions with the class, so you might get removed if you disrupt things and block others from learning.
It's fine. I won't distract anyone.
But these classroom meetings are meant to be shared and understood by everyone.  It can be fun to have private conversations with your friend in a secret language, but those should be done privately, outside of classroom hours.