Hi,
The pubs database is a sample of a publishing company, which includes books, authors, sales and stores.
It includes the tables: authors,publishers,titles,titleauthor,stores,sales,roysched,discounts,jobs,pub_info,employee
here you can see the diagram of the database:
For more information you can simply go over the scrip which create the database and all it's entities:
https://github.com/microsoft/sql-server-samples/blob/master/samples/databases/northwind-pubs/instpubs.sql