means A staff is either a long stick used for support, defense, or as a sign of office, or the group of people who work for an organization.

from From Old English 'stæf,' meaning a walking stick or rod — a word with deep Germanic roots, kin to Old Norse 'stafr' and Dutch 'staf.' The original sense was purely the physical pole. The 'group of employees' meaning is much later, an extension via the military 'staff' — the officers who assisted a commander, imagined as the support on which leadership leaned, much as one leans on a stick. The musical 'staff' (the five lines of notation) borrows the same image of horizontal rods.