In the article they have explained how to add custom product fields, BUT I didn’t understand in that code for which specific product…
I mean for which product page, they’re adding custom field?
To be more clear, where to add my product id in that code so that my custom fields would appear in my required product page?
Sorry, if it’s a dumb question (I am not good at PHP).
They are just showing you a way to add custom field in your edit product/ add new product page under general tab. The output will show on Single product page and Optionally they have shown you the code to show it on product archive pages, if you want to. Archive pages include shop, product category, product tag etc.