Hello, the values help you to know which fields to choose and how will you use them from …/categories/list & …/products/list, it is mainly for reference purpose. You may ignore all optional parameters first to get results.

https://apidojo-hm-hennes-mauritz-v1.p.rapidapi.com/products/list?categories=ladies_dresses&sortBy=stock&concepts=H%26M MAN&country=se&lang=sv&currentpage=0&pagesize=30

this returns zero results! why? even your own example in product list returns zero results!!