This feels like one of those things that's kind of a confirmation of existing common knowledge. If you have dogs, you are probably very aware that dogs know certain words and develop expectations around routinely used words and actions. For example, running through a list of words my dogs know and gauging their reactions will tell me exactly what they want nine times out of ten.
Dog boops. "Food?" ... "Water?" ... "Outside?" Tilt "You want outside?" Dogs stampede to door
It's kind of wild how much they understand of vocabulary, but add in the way they read faces and body language, it's frankly amazing.