It's good to offer help to your friends.
Mark is talking to Lou who casually mentions that he's getting ready to move on Saturday.
Mark wants to say something about how hard moving is.
Mark tells Lou that moving is extremely difficult and if he wants he can help him move to make it easier.
Mark tells Lou that he's in for a hell of a day since moving is one of the worst things a person can do.
Lou is delighted Mark is offering to help him move and gladly takes him up on it.
Lou is not amused that Mark is stating the obvious and is almost rubbing it in about how hard it'll be.