"行政上的职能" can be translated as "administrative functions" or "administrative roles and responsibilities" in English, depending on the context and the level of specificity required.
"Administrative functions" is a more general term that refers to the duties and tasks associated with the administration or management of an organization, department, or system.
"Administrative roles and responsibilities" provides a bit more detail, specifying not just the functions but also the roles and the associated duties that come with them.
In most cases, "administrative functions" would be sufficient and commonly used.