This is the 405th most frequent Bulgarian word.
каква
The Bulgarian word "каква" means "what" or "what kind of" (feminine form).
The word 'каква' is used here to ask about the nature or specifics of an object, in this case, the book being read.
Каква е книгата, която чете?
What is the book that you are reading?
In this context, 'каква' is used to inquire about the type or kind of something, specifically the melody in this example.
Не знам каква мелодия звучи.
I do not know what kind of melody is playing.
Here, 'каква' is used as an exclamation to emphasize or express admiration about the evening.