Reply To: Showing only the products from a certain category in the sidebar

Hello,

These are related products. Related Products is a section on some templates that pulls products from your store that share the same tags or categories as the current product.

These products cannot be specified in the admin, but can be influenced by grouping similar products in the same category or by using the same tags.

Here is the documentation how it works:
https://woo.com/document/related-products-up-sells-and-cross-sells/

Best Regards.