By itself, it just means "I..." At the moment, you have no verb with it. "I am." would be "내가 예요." I'm not that great at Korean, but that sentence sounds really weird to me.

Hi Vanny, 내가 cannot be used by itself. There should be verb after that. Ex. I'll take it. = 내가 가져갈게. I am the person they talked about. = 내가 걔네가 말한 그 사람이야. "I am." may be translated in different ways depending on sentences. Ex. A: Are you a student? (=너 학생이니?) B: Yes, I am. (=네, 저 학생이에요.) A: Are you going out for dinner tonight? (=오늘 저녁먹으러 나갈거니?) B: Yes, I am. (=네, 나갈거에요.) Hope it helps..

not much to say here...except: What you should know so is that the -가 marks the subject. The "personal pronouns" (나, 너, 저 ~ I, you, I) 나, 너, 저 + 가 =내가, 네가 (what can be spoken somewhat like 니가), 제가