Hi @pinkcricket
That section would be for the more technical details of your product. General example here if you scroll down the page. I don't use Square Online, but you should be able to drop elements (from the side?) such as text, images, videos, and more . This section is great to use for extra information about the product and to help build your SEO for that product.
I hope that clears up your question, and if not, just let us know!
