A good question
If it was the first statement of a conversation, I would understand it as "hello" or "hi" and yet I'd reply with "hello" or "hi." If it was not the first, I would understand it as "how are you?" or "how are you doing?" and yet I'd reply with "I'm ok" or "I'm fine" and so on.
* NOT A TEACHER NOR A NATIVE SPEAKER
Waiting for a native speaker to explain the suitable answer
Student or Learner