"Her color is pink."
Translation:Haar kleur is roze.
Because "roos" is only used in specific areas, whereas "roze" is standard Dutch. That does not make "roos" wrong in the regions where it is being used. But for the purpose of learning a language it is best not to confuse people with all the words that regionally can be used.
As a guide Van Dale defines "roos" as:
The flower rose
Bullseye of a dartboard
But not as a colour. As said that is "roze"