"The lamp is on the desk."
Translation:Lampa stoi na biurku.
Yes, it denotes the way it is situated. We generally want the lamp to be 'standing', if it's lying then it probably means it was knocked over. Okay, that's not the only context, but still. It isn't placed as it should be.
So perhaps we should leave "Lampa leży na biurku" for the explicit "The lamp is lying on the desk", because that really needs some more context.