section staff; member of a section
Refers to a person who belongs to a 課 (section/division) in a company or organization. Neutral, everyday business term.
He is a member of the sales section.
All the section staff attended the meeting.
The section chief informed the staff of the new policy.
All the section staff gathered for the meeting.
部員 refers to a member of a 部 (department), a larger unit, whereas 課員 refers to a member of the smaller 課 (section) inside it.
社員 simply means a company employee in general, while 課員 narrows this down to someone belonging to a specific 課 (section).
The everyday counter for people: 一人 (ひとり), 二人 (ふたり), 三人 (さんにん).
More formal than 人 — used for headcounts in reservations, staff lists, and announcements (5名様).
Compound of 課 (section, division) and 員 (member, staff).