It is kind to help someone understand something.
Dave is working away at his desk at his job when his coworker Frank asks him to come to his desk to help him make sense of a file.
Dave wants to respond to Frank's request.
Dave tells Frank that he'll be over in a few minutes, and he can take a look at the file for him.
Dave tells Frank that he's quite busy right now and that Frank should already know how to do the job anyway.
Frank is delighted that Dave will help him out and relieved that he'll get the file figured out.
Frank is insulted that Dave is suggesting he doesn't know how to do his job and annoyed he can't get assistance.