This was a spam caller with a foreign accent asking "Can you hear me?". This is a scam call, do no answer and do not say yes.

What can you do if you did say yes?

Move on with your life and not worry about it.  There has never been a recorded, verifiable case where anyone was every scammed using that word.  Not only that, there are no situations where only that word is needed to open up accounts of any sort.