A staff member or attendant in charge of a particular task or duty; an official who handles procedures or provides assistance.
電車の事故現場には係員が数名待機していた。
Several attendants were standing by at the train accident site.
受付で係員にチケットを見せてください。
Please show your ticket to the attendant at reception.
美術館では係員の指示に従ってください。
Please follow the instructions of the attendants in the museum.