noun
Typically refers to a staff member who handles cleaning, maintenance, and odd jobs in a school or public facility.
学校の用務員さんが廊下を掃除している。
The school janitor is cleaning the hallway.
管理人 is a broader term for a manager or superintendent of a building, while 用務員 specifically refers to a janitor or caretaker, often in a school setting.
Compound of 用務 (duties, business) and 員 (member, staff). The exact historical derivation is uncertain, but the word is conventionally associated with a staff member responsible for miscellaneous tasks.