brother Hanfi means according to the teachings of Imam Abu Hanifa. There are four Imams Imam Abu Hanifa, Imam Ahmed bin Hanmble, Imam Malki, Imam Shafai(I may put some wrong name but i tried to be correct according to my memory). All these four Imam's teachings are right which ever u want to follow u can follow. Most of Subcontinent muslims follow Imam Abu Hanifa's teachings, thats why Hanfi is written on the books.