Traslation issue

Good morning,
I am using your pluging Rank Math and it is a good experience for the moment, I hope that I will see good result online in ranking soon.
I have a question, before I check in many topics and I understand that the tags of the second language (Using Polylang) will not appear in sitemap but google will find it. I check it and it is true, google put it in the coverage as, indexed but not submitted.
But I have a case that I am not sure what to do:
Basic language of the site is Spanish, second language is English, but I have some product that I can offer only in English, so the Spanish version doesn’t exist. So how the Rank Math will build the sitemap in this case?
Note that the products are tours for tourists, and in some cities, I have contact only with English speaking guides and it will have no sense to put tours in Spanish.
Hear from you.
Thank you for your time.
Best regards