"A man is charming."
Translation:남자는 매력이 있습니다.
이/가 join onto the subject of the sentence IF the sentence doesn't follow up after another
Example "남자(가) 여자 없습니다" The man is not a woman, let's say that the sentence started the conversation.
If we used the sentence mid-conversation, it would change to: "남자(는) 여자 없습니다" The man is not a woman
는 would be used because the particle is "comparing".
So, to answer your question, 매력 is an adjective. So it does not get 이/가 & 는/은 added to the word.
The topic particles 은/는 don't relate to English articles. If you're asking because you used "the" and it was rejected, that's because they need to add that sentence as an accepted answer still. In other words, here, "a man" and "the man" are both acceptable.
는 and 은 only tell you which words are the subject (i.e, "I" in "I eat rice"). They have nothing to do with a/the, they were simply dropped from the translation.