FaceTime set up for my son who is 10 years old

Start here:

Help your child set up an iPhone, iPad, or iPod touch - Apple Support

Being only 10 years of age, you’ll be setting-up their AppleID account as a minor. You may find this information to be helpful with setting-up an AppleID for a minor - and considering appropriate controls:

Apple for Kids - Official Apple Support

Help your child set up an iPhone, iPad, or iPod touch - Apple Support

Family Sharing and Apple ID for your child – Apple Support

Use parental controls on your child's iPhone, iPad and iPod touch – Apple Support

Once set-up, your son should be able to use FaceTime within any restrictions that you have applied.

Has you email provider switched to using App Specific Passwords? If so, you will need to generate a unique password for your iPad email account - that will differ from your normal Account Password. As examples - AOL, Yahoo, Google, Microsoft all use App Specific Passwords when using anything other than their own email client Apps.

If you need to generate an App Specific Password, you’ll need to log-in to your Mail Providers account management webpage - using a web browser - and generate the Password from the appropriate account security page.

More information about AOL’s App Specific Passwords can be found here:

https://help.aol.com/articles/allow-apps-that-use-less-secure-sign-in?guccounter=1

For Yahoo, more information can be found here:

https://help.yahoo.com/kb/SLN27791.html

For Gmail:

https://support.google.com/mail/answer/185833?hl=en-GB

Microsoft:

https://support.microsoft.com/en-us/account-billing/using-app-passwords-with-apps-that-don-t-support-two-step-verification-5896ed9b-4263-e681-128a-a6f2979a7944

If using a Gmail account, the issue is almost certainly the need to create an App-specific password for email. The App-specific password can only be created from within the Google account.

https://support.google.com/mail/answer/185833?hl=en-GB

To be clear, the App-specific password is just to access email from non-Google Apps.

Have you added your son’s email account to the iPad?

Add an email account to your iPhone, iPad, or iPod touch - Apple Support

You’re very welcome.