Dogs learn in several ways, one of which is association. They associate an experience with an emotion. 

What is transfer of value?  Let’s use the example of teaching a dog to “sit”. If you give your dog one treat for sitting, they’ll enjoy that treat. If you give your dog five treats, one after the other, while their bum is on the ground, they’ll LOVE that. There’s a lot more value in those five treats than the single treat. They’ll learn that “sit” is the coolest thing going. They’ll WANT to sit. They’ll be motivated to sit. Over time, sit itself will be rewarding because of the reward history and transfer of value.