What is the Schemas JSON object at the bottom of the API page?

Completely new to Swagger, and got handed a Swagger file trying to figure out what the Swagger Editor is showing me. At the bottom of the API, there is a "Schemas" section that has definitions for a bunch of JSON objects. What are these for?

The top part has the API with POST/GET requests, but what is this 

components:
  schemas:
    <json objects with descriptions...>