Adding an email account

It is asking for the email account password.

Assuming you are adding a new gmail account, create the account on the gmail webmail page including creating a password for the new gmail account. Then when adding this account to the Apple Mail client, use the password for the new gmail account. The same process should be followed for any new email account. You need to create the email account on the server including a password for that account. Then add the account and password to Mail.