You will always find that a person with very little learning loves to jabber all the while and laugh and joke and make a lot of noise. Because the person doesn’t really have any substantial matter in the head and so hides this fact with a lot of meaningless chatter. But the person of real substance looks around, observes and when he or she speaks it is to say something really meaningful. that is what is meant by this proverb.
Hence when we are in a conversation we should only take a fair share of the conversation and not keep prattling on as if no one else people’s opinions and wish to hear them out too. It would also give the impression that we are not big mouthed who really bore the others with our pompous talk