What Your Dog is Trying to Tell You

Words may be important for humans to communicate, but dogs convey emotions through body language and sounds.
While your dog may seem to understand your words, especially if you've put in the effort to train them on simple commands such as sit, heel, and stay, you also need to work to understand and translate canine body language.

Canine:
relating to or resembling a dog or dogs.

heel:
the back part of the human foot below the ankle.
a command to a dog to walk close behind its owner.

From here