WP_Post object summary
The WordPress post object is an array of data with everything in the post.
data contained in the object
The WordPress post object contains all of the data such as the author, date created, its excerpt, and all of the information about the post.
Post object role in the page load
The role of the WordPress post object on page load is to bring back the information that the developer has decided should be shown with the post when a user clicks on it to read it.
Summary
The WordPress post class holds all of the WordPress post objects in the database and it can be called with the get_post function.