Activation lock

Enter the email address and associated password it's asking for. If you don't know these, you will forever have a useless brick.

If you purchased this from some unknown person locally or online and they can't, or won't provide this information, then you likely bought a lost or stolen phone. No one here can help you. Apple will not unlock the phone without proof the phone belongs to you. And that would be a copy of the original purchase receipt showing the matching serial number.

If this is your phone, and you've simply forgotten this information, start here:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Contract the previous owner and have them follow these steps: https://support.apple.com/en-us/HT201441

Until activation lock is removed, you will not be able to use the device.

Yes, that is a lie. Only the carrier can activate a SIM. If you know where this person is, return the watch and demand a refund.