Email already exists message

1. What does email already exists mean?
2. What does your contact email is already set to that email address mean?

What does email already exists mean?

If you receive an error message (such as, "Google Account already exists") as you're trying to set up your first Google administrator account, it means that the email address is already associated with another Google service (such as an AdWords account).

What does your contact email is already set to that email address mean?

Answer: This error message means that there already exists an account registered with this email address.