Every action and word that another person observes reveals a part of oneself or one's motivations to another, and thus, it communicates a message or rather a meaning to the observer.
I would say true, considering when observing someone, you typically are able to watch their body language and motions that convey hidden messages. For example, watching someone talk to another person, who just happens to be moving their hands a lot, could mean that they tend to emphasize their words. These unconscious movements could, in theory, send messages to those watching.
