I don't think so, because it's telling about I am his younger sister. The meaning of your sentence is telling about " 나는 누나입니다."

if you man, younger sister : 여동생 older sister : 누나 younger brother : 남동생 older brother : 형 if you girl, younger sister : 여동생 older sister : 언니 younger brother : 남동생 older brother : 오빠

You seem to be confused about "나" and "내". 나 = I 내 = my In fact, we seldom say "나 여동생이에요" when it means "I am a younger sister". "나는 여동생이에요" is a full sentence. If you say "내 여동생이에요", it means "she is my younger sister."