One could conjure up an image in their mind of a happy young married couple just starting a family, living in a house with a white picket fence. On the other hand, the picture of a jealous abusive boyfriend may pop up. When one reveals his feelings about another person to that person, the other person is going to feel something. Think of every emotion, surprise, shock, anger, love, joy and happiness. Now thing about how much these emotions are evoked by words.
Words bring peace, mostly when language reveals truth.
One can feel peace when reading the Bible, having God's promises communicate repeatedly. After all, peace is freedom from disturbance. Words say so much. It is the communication of an emotion. It can be a dream for the person hearing it, a hope that the other person will say it back, and it can also be perceived or meant as a commitment.