The General tab has 4 fields: Name, Post Type Slug, DB Table, and Color.
Name: This is name of the post type and is used to identify what it is. It’s advised to be plural. e.g. Restaurants, People, or Contacts.
Post Type Slug: This is the slug of the post type and will be used in the URL examples of post type slugs is “page” and “post”
DB Table: This is the table that the post type is connecting to. You can only connect to a table that has a primary key and is highly advised that this is an id field.
Color: The color is simply a setting to make it look pretty in the admin page and the post type entry list page.