What does the Editorial Department for film production companies do?

I am going to be interviewing for an internship at the Editorial
Department of Columbia Pictures for a film being shot close by. I am
very excited and love every aspect of film-making, but I am not very
clear on what exactly the Editorial Department does. Obviously they
cover a lot of different bases, but can anyone tell me what they are
generally responsible for? I know i'll be doing a lot of driving and
gopher work (which I'm not complaining about), I just want to be at
least somewhat knowledgeable about the department during my interview.

Thanks!