"que lindo" is a Portuguese language word and the meaning is "Cute" So if you want to compliment someone, as Cute. You can just say "que lindo" and surprise them. Words can make an impact, it can be good or bad that depending on the choice of words.
We have so many different languages in the whole world, people should use different languages sometimes as it can increase their knowledge and at the same time, you can impress people by using different words.