Something indirect is not hitting the target exactly. Indirect sunlight doesn't shine right on you — it reflects off a window or is muted by a shade.
If direct makes you think of a straight line, then indirect looks like a crooked one — there are turns and stops along the way. People who are sneaky might get what they want through indirect means, like going behind people's backs. If you go to school using side streets and back roads, that's an indirect path. Anything indirect is not taking the quickest or shortest route, but sometimes being indirect gets the job done.