How do I restore safari app to my ipad air?

You cannot remove Safari, if you are unable to see it, you may have turned on restrictions and it is an app that is restricted which will cause it not to show. Make sure you check your restrictions section and make sure it’s either turned off, or Safari is turned off and it should show back up.

Safari can’t be deleted, so it’s somewhere on your iPad. Check carefully on each home screen and - especially - inside all folders.

If you still don’t see it, check if it’s restricted from view:

Settings > General > Restrictions.

To reset home screen layout on your iDevice:

Settings> General> Reset> Reset Home Screen Layout.