Could you provide some context? It could be a typo. «Замдиректора» (заместитель директора) is indeed a word in Russian, and it means "a director's assistant, deputy". A person who assists your CEO and takes charge when the real boss is somewhere else.

ChadyArc answered you exactly, but i have to add to it , that usually we point the specific issue if assistance in that title . Замдиректора по строительству ... it means that assistant supervises constructing in that company. Замдиректора по безопасности... he supervises safety in that company