If your account is registered to Supercell ID, just log in to your Supercell ID from your new device.

If your account is not registered to Supercell ID, access your game from your other device and:
1.Go to your game’s Settings
2.Tap on ‘Sign in with Supercell ID’
3.Register using a secure email address
4.Type the verification code which is sent to the email address

When ready, go to your other device and follow the steps above. Your account should now be transferred.