@Ana19013
A review is not the same as the rating. Allthough they belong together, the review appears on your listing for the general public, the rating not.
The review from A. says (translated): "not bad" (which is a really short review...). You can ask this guest why he rated you 3 stars (to at least have a clue why he rated you 3 stars). But there is not much to do about it, airbnb will probably not remove the review or change the rating, if you ask them to do so.
best regards,
Emiel