The bags contain charcoal for cooking fuel. They are sitting alongside the road awaiting a buying customer. This is a very common sight throughout Kenya.
I think you can see the interesting contrasts. Their homes are built of sticks (or sometimes mud) - both of which are an earth-brown color.
Then there's this almost contradictory splash of color - yellow for the roofs, or sometimes white plastic pieces (used here to assist the wind protection of the fence).
I guess, all over the world, people groups use whatever materials are at hand to construct some sort of roof over their heads and shelter from the elements.