Correct spelling for the English word "NKFVAS" is [ˌɛnkˌe͡ɪˈɛfvˈas], [ˌɛnkˌeɪˈɛfvˈas], [ˌɛ_n_k_ˌeɪ_ˈɛ_f_v_ˈa_s] (IPA phonetic alphabet).
I apologize, but "NKFVAS" does not have an established dictionary definition as it appears to be an acronym or a term that does not have widespread usage or recognition.