Either you have some relict s turned on in Settings or you inadvertently dropped Safari on top of another app while moving it, or dropped an app on top of Safari. Either of these actions created a folder that contains Safari and the other app or apps.
In addition to checking restrictions, you can go to settings, general, reset, reset home screen layout. That will return everything to the way it was when new. Or, search for it to find out where it went.