Products are the physical goods, digital files, and services that you sell. To create a product, you need to specify the name and upload product images. In addition, you can add product details that help your clients better understand the product: add description, available sizes, weight, etc. You don't have to provide every detail for each product.
Kindly access the following links for a more detailed write-up on "how to add product to your online store”: https://support.ecwid.com/hc/en-us/articles/360000009240-Guide-to-product-details.