A dogs snout is referring to their nose and the front part of their face. They typically refer to this part in behavioral training on many different breeds of dogs.
A dogs snout is a combination of the mouth, jaw, and nose which protrude from the head of the dog. The snout starts just under the eyes and ends at the tip of the nose.
The snout goes from the tip of the nose to the eyes but not including the eyes. The easies way to tell the snout is to look at where a muzzle is on the dog they usually cover the snout.