Sorry. I need help understanding. If I need a password to sign into something like a gmail or comcast account, w a password,Apple can’t see that information?

Apple cannot see your passwords even if you save them via Safari in the Keychain and the Keychain is sync'd between Apple devices via iCloud. There's several layers of encryption that use public/private keys generated based on your device hardware and your login password to the Mac or mobile device. When the keychain submits the password on your behalf it is encrypted in transit by Gmail / Comcast encrypted website or email server connection.

Apple Platform Security

https://support.apple.com/guide/security/welcome/1/web

If you drill down through the Table of Contents you can deep dive on the security Apple employs to protect your privacy. On either a T2 equipped Mac or the new M1 based Macs as well as all the mobile devices the security is even greater. Apple cannot see your passwords even though they are sync'd via iCloud. Apple has some of the best security measures available to the general public.

Using app-specific passwords

Why is Mail asking for your password?

• Your email provider needs you to update or reset your password for security reasons. For example, if you're using Google’s two-step verification, your Gmail account in Mail requires the appropriate app-specific password.
• Your email provider deactivated or suspended your account. Contact your email provider for help.