From which end (north or south) of a bar magnet do magnetic field lines emerge? Do the field lines really start at the pole face? Do magnetic field lines ever start or end anywhere?
Magnetic field lines are representative points of the behavior of a magnetic field through space.
Magnetic fields are mathematical tools that we can use to describe magnetic forces that are induced onto objects. Magnetic fields are responsible for the forces at play when we see magnetic attraction or repulsion in bar magnets.
Just like with electricity, magnetic fields can be generated by moving electric charges. The same charges that produce electric fields can also produce magnetic fields, so there is no such thing as a strictly magnetic charge.