A 'lit torch' represents a significant action, a crime, or a profound truth. A 'grass hut' represents a fragile, flammable attempt at concealment. Eventually, the fire of the truth will catch the dry grass of the lie, leading to total exposure and the destruction of the hiding place. It teaches that certain choices carry an inherent visibility that cannot be managed or contained by deception.
You cannot hide a lit torch in a grass hut. The truth will inevitably demand to be seen. The heat of the reality will always consume the shelter of the lie.