Quotations and Literature Forum

Can anyone help me understand this?

I believe it refers to people who often like to talk, but say nothing useful. The hint is that they should probably not say anything at all

Thanks

I wasn't sure though if it was more to do with keeping a dignified silence because that speaks volumes - or something like that.

I like this explanation, never would have thought of it like that!
I was thinking more of people who don't say a lot yet have a lot to say, if that makes any sense.