Question

a brief account between the friendship of princess September and the nightingale

Answer 1

The nightingale offers himself as a companion to the princess in place of her parrot. But she shuts him up in the cage, so she could have him with her all the time. But friendship is not selfish it demands sacrifice. So when she realizes the true meaning of friendship, she set the bird free and sacrifice her own wishes, just to make the bird happy again