What does this traffic sign combination indicate?

You answered correctly. This sign combination uses a general warning sign with an additional plate showing a horse and carriage. It means there is a danger on the road specifically connected to horse-drawn carriages, so drivers need to be extra careful and ready for slow-moving or unusual traffic. It does not give priority to horse and carriages, nor does it prohibit them from passing through—it's just a warning for their presence. Understanding such combinations helps you anticipate specific hazards ahead.