The shop does not have sections where you can enter your own SEO or metadata (title tag, description tag, keywords) like the other pages. Instead, they use the content and titles you have used in the articles/products to create their own metadata.
The meta title and meta descriptions are generated from the main heading of your shop product name coupled with the first 200 characters written. If you are wanting to change what is viewed as your SEO information for these pages you would just need to adjust the first product title and product description.