encryption password

If you are backing up health data along with others then the iTunes Backup will require a password which you will need it while restoring from this backup

Back up your Health data on iPhone

• If you use iCloud (see Sign in with your Apple ID), your health and fitness information in the Health app is stored automatically in iCloud. Your information gets encrypted as it goes between iCloud and your device and while it’s stored in iCloud. In addition to using iCloud, or if you aren’t using iCloud, you can back up your Health data by encrypting an iTunes backup. See Back up iPhone using iCloud.

Back up your Health data on iPhone - Apple Support

https://support.apple.com/guide/iphone/back-up-your-health-data-iph11f1eb698/ios

Take a look at the following article. In particular, scroll down to 'If you can’t remember the password for your encrypted backup'.

About encrypted backups in iTunes - Apple Support