Speech is probably the most important means of communication for humans. Dogs are different: “speech,” in the sense of barks, whines, howls and other sounds is less crucial for them than many other aspects of their communication.
Instead, they use tails, ears, whiskers, mouths, and posture to tell us what they are thinking, and, once you have some idea of what to look for, they are astonishingly eloquent. For example, you can read a lot of basic information about a dog’s mood from how he or she is standing, and the shape of his or her back.
Legs and paws are also used expressively, and both backs and legs are relatively easy to “read” for the onlooker; they give broad information that you can augment by looking at what the ears, mouths, tails and eyes are doing. A square, stiff stance on four braced legs is forceful, the sign of a dog that is highly reactive for one reason or another; “easier” poses, with legs placed rather than braced, are more relaxed.