Yes, it is. "누난" is short for "누나 + 는(subject marker)". Contraction with markers often happens in spoken.^^' 나(subject) + 는(subject marker) = 난 나(subject) + 를(object marker) = 날 누나(subject) + 를 = 누날 "너무(=too)" has to be "아주/정말(so)" in the sentence because "너무" is usually used in negative sentences but very often used in positive sentences in everyday Korean as well. \^o^/

///Why is it 누난 (isn't it 누나 ?) 누나는/누난 너무 예뻐. You're too beautiful. 나는/난 나야. I'm me. 너는/넌 너야. You're you. ///What does 너무 mean in this sentence ? too 누난 너무 예뻐. You're too beautiful. There are too many things. 물건이/그것들이 너무 많이 있다 너무 많은 것들이 있다.