Long description in rich text. Here you can write the fine details of your products. The terms and conditions, return policy for this specific product, etc.
(External/Affiliate Product) Product Name Here
This is an External/Affiliate Product, so you easily can link to your own eCommerce store products.
Short description of the product.
This will be closer to the picture and on the top part of your product page.
This helps search engines like google to find you better as well. So be as good at describing your product as possible. That is called SEO = Search Engine Optimization.