and what is the slug?

Hello,

Product to buy: Which product customer need to buy
Product to get: Which product will get get for free, if he buy above product

Slug is a part of the URL when you are accessing a resource

Thank you

I see that "product to buy " and "product to get " is set data type int.However , as you say, the data type should varchar.

About slug , I do not understand

It's not useful for you, if you don't have shop module. Slug is used to generate url for products and categories in shop modules. Please check the attached screenshot. Thank you

Yes, I do not have shop module.