The partnership between visually impaired humans and guide dogs allows each partner to achieve things they might struggle to do alone. To move safely through a world designed by and built for sighted humans requires trust and communication.
A language has been developed to help humans and dogs understand what the task is and how to complete it. This language is not just made up of words but a complex system of gestures, touches, feelings and sounds. This was developed over years by guide dog trainers and owners and guide dogs themselves.
You can learn some of this multispecies language yourself with this short game of doggolingo.