Hi bobc20xb,
We understand you're being asked to enter the password for an unknown email account when you're trying to restore data to a new device. We're happy to help.
If you're being asked to enter a password for an account that you're not familiar with when you're in the process of restoring a backup, this would mean there is something in the backup associated with that Apple ID email. Whenever you purchase or download anything from the iTunes or App Store, the Apple ID it is downloaded with is associated to it. It's asking you for the password to that Apple ID because there is some item in the backup that was purchased/downloaded with that Apple ID. This could be an application, music, a movie, a tv show.
Your best course of action is to just skip over that prompt and continue with the restore process. Whatever was associated with that Apple ID just will not be restored to the device. When the device has finished restoring and you're at the Home screen if you notice something missing like an app, music, movie, etc, that will mean it was the item associated with that Apple ID and you can download or purchase it with your own Apple ID if you need it back,
Hope this helps. Cheers!