Forteressed is the adjectif of the noun Fortess. Forteress ( حصن ) mean a fortified defensive structure that means in arabic ( بنية دفاعية محصنة ) Forteressed profil mean that you can't go into the profil because it is immune

It means only certain people can access it. Another way of saying it is Limited Profile where only your friends have access to your profile, eg Facebook.