Create a new Product Extension

Navigate to Configuration > Product Master Extension

Create a new Extension (table)

Setup the columns you need

Hide all unused columns

Log out and Log in (to see your new Extension on the next screen)

Access the Product Extension

Navigate to Product Extensions and select your new extension

Add data to Product Extension

Add couple lines for existing Products (or import from Excel file)

Add the Extension to Product Detail page

Navigate to Detail of a Product

Add your new extension to a detail of Product

Now you can see your extension on the Product Detail