Here it is word for word:
A verbal te-form verb plus ' mo ii desu ' means "you may do..." , which describes an activity that is permitted. To ask for permission, you can turn it into a question sentence, ' ~te mo ii desu ka'. If somebody asks for permission and if you want to grant it, you can either repeat the while verb te-form plus 'mo ii desu' construction, or just say 'ii desu'. 'Te mo ii desu' and 'ii desu' do not stand alone.