Proficiency
Being trained in something. Trained characters add an extra bonus to rolls with it.
A character is proficient with the weapons, armor, skills, tools and saving throws their training covers. When they are, their proficiency bonus is added to the roll. The bonus grows with level.
In Fantasy RPG
Fantasy RPG proficiency bonus: +2 at levels 1–4, +3 at 5–8, +4 at 9–12, +5 at 13–16 and +6 after. It is added to attacks with trained weapons, trained skills, the class's saving throws and trained tools.