Sorry if it is confusing.
What does a Starbuck serve?
or
What do Starbucks serve?
The second one makes sense for me, since there are many Starbuck shops, but I'm still uncertain.
Which one should be grammatically correct?
Sorry if it is confusing.
What does a Starbuck serve?
or
What do Starbucks serve?
The second one makes sense for me, since there are many Starbuck shops, but I'm still uncertain.
Which one should be grammatically correct?
The name of the company is Starbucks -- it is never written without the 's', whether you are speaking of the singular company, a single shop, or multiple shops.
If you are speaking of a single shop, use a singular verb:
What does the Starbucks on the corner serve?
If you are speaking of multiple shops, use a plural verb:
What do the Starbucks in Minneapolis serve that other Starbucks don't serve?
If you are speaking of the company, AmE use calls for a singular verb:
What does Starbucks permit its stores to serve?
I would actually just say What does Starbucks serve?
I think this, because Starbucks is a singular noun. Starbucks is a chain of stores. I think typically it is unnecessary to ask about one particular store, because a chain of stores all serve the same thing (almost).
I would think if someone asked about just one store that they were asking what that store serves that is different from all the other stores.