assistant to the general manager; staff attached to the department head
A job title for someone assigned to assist a 部長 (department head/general manager). The role is often administrative or secretarial.
As an assistant to the general manager, he is in charge of schedule management.
The work of an assistant to the department head covers a wide range of tasks.
秘書 is a secretary in general, while 部長付 specifically denotes an assistant assigned to a department head, often with broader duties.
Compound of 部長 (department head) and 付 (attached, assigned). The reading づき is a rendaku form of つき.