Throughout the movie, all of the protagonists gain the noble sign of being ready to make sacrifices for that good of some other.
Elsa sacrifices her happiness to help keep Anna safe. Anna is ready to give up her life to be with her sister. Kristoff gives up his chance of true love to ensure that Anna might be happy. Olaf the Snowman helps Anna, Kristoff, and Elsa discover how to end the perpetual winter in spite of the realization that warmer temperatures will finish his life.
While not every the sacrifices within the movie possess the conclusion the characters were expecting, their willingness to sacrifice for that benefit of or their loved ones is a good moral lesson parents want their children to know.