What applies with this traffic sign?

This sign means you must pass an obstruction on the left side. It indicates the mandatory direction in which you should drive to safely avoid the obstacle. It does not mean you must make a left turn at an intersection, nor does it prohibit turning right before the sign. Instead, it controls the path around an obstacle on the road to keep traffic flowing safely and clearly. Remember, blue circular signs with white arrows in Germany typically show mandatory directions to avoid hazards.