Sign 1 is no overtaking (all types of motor vehicles are prohibited, are allowed to pass two-wheeled motorcycles, mopeds).
Signal 2 is forbidding trucks to pass (prohibiting all types of overtaking). Trucks with the largest weight over 3,5 tons overtaking other motor vehicles, are only allowed to overtake two-wheeled motorcycles, mopeds); while other motor vehicles are allowed to pass each other and overtake the truck