This sentence is WRONG! I reported that.
There is no "a" preposition here. The preposition is "sobre".
The only possible way to write "sobre a" in Portuguese is when "a" is an article.
It could be "E quanto àquele café". Then it would be right, because "quanto a" exists being "a" a preposition.
So far it has been hard for me to learn portuguese from english when my native language is spanish, but I cannot accept this wrong sentence, from all my points of view this is completely wrong. I understand they're asking about some coffee like they were asking if someone is going to accept an invitation to have some coffee for example . I need someone to explain this for me please!!!
There is no need to learn Portuguese indirectly via English. Have a look at the Portuguese for Spanish speakers course currently being tested: