Resistance (魔防 Mabō lit. Magic Defense) is the Fire Emblem statistic that defines a unit's ability to defend against magical attacks. Higher the resistance less damage the unit will get by magical attacks. It is high in magic users, especially Monks.
In most early Fire Emblem games only mages would have a resistance growth rate. Non-magic units usually have very low resistance, much like magic units have very low defense. In most games resistance can be boosted by two points with a Talisman. However, Pure Water and a barrier staff can temporarily increase resistance by 7 points. Nini's Grace, is used by Ninian or Nils in Fire Emblem: Rekka no Ken, to increase resistance by 10 for 1 turn.