What dose it mean your yahoo ID exist?

Question

What dose it mean because I have a cousin that haves a yahoo ID exist.

Answer 1

I'm not sure I understand your question. Was your cousin trying to sign up for a Yahoo! account and was told that the ID your cousin wanted already exists? If so, that means that someone else already has that ID and your cousin can't have it. Two people can't have the same ID. Your cousin has to choose a different ID.

If that's not what you mean, please add details and explain your question.