Hello Eli, I'm Toni, from HK, nice to meet you here ;)
I'm afraid I don't know what dose it (silence speaks volumes) mean.
But what I found another nice saying was 'silence is golden'.
Which means it is often best not to say anything
well, anyway, I hope I could have helped!
Do you want to be a friend with me? we can share our experiences anytime.
Student or Learner