Historical term for an instructor or guide, especially in traditional arts, martial arts, or Edo-period contexts. Not used in modern everyday Japanese.
In the Edo period, instructors taught swordsmanship to samurai children.
指導者 is a general modern word for a leader or instructor in any field, whereas 指南番 is a historical term with a narrower, traditional connotation.
Compound of 指南 (shinan, 'instruction, guidance') and 番 (ban, 'watch, guard, person in charge'). The exact historical derivation is uncertain, but it likely referred to a designated instructor or master in a specific domain.