The literal translation of the title of this movie is: the Fifth Sister.
This movie is loosely based on the true story of the life experience of a forest teacher, who gave up the good life, higher salary, and better welfare in the coastal cities and voluntarily went to the remote mountainous region of southwestern part of China to teach ethnic minority kids. The teacher endured harsh life that was unimaginable to those who lived in the relatively wealthy eastern coastal cities, and finally earned the respect and love of the locals and eventually true love and romance.
However, when the original script that was accurately depicted what happened was sent to for evaluation, it was rejected by the governmental censorship because the government was afraid that such honest depiction of harsh life would discourage people from helping those in the remote regions of China, and script was forced to changed to the current one that put much more emphasis on the romance than the harsh life.