Propp's application of structuralist methods to the study of Russian folktales is one of the first instances in which a theorist used structuralism to analyze narrative. If you read the book, chances are you'll be able to understand any and every plot possibility for every fairy tale and folktale ever.
Some questions to think about as you read:
(1) How does Propp break down the elements of each folktale to arrive at a general understanding of the structure that underlies all of these folktales? Why are there as many elements as Baskin Robbins flavors?
(2) How applicable is Propp's methodology to the study of other types of narrative? Think of the novel as opposed to poetry, for instance.