What is the function of horse's tail in the movie?

The role of ponytail is about the movie "Break". In the movie, the professor stood on the platform, and a color picture of a horse hung on the blackboard. The professor began to point to the color picture to talk about the role of ponytail, which attracted the college students to burst into laughter. Ge Cunzhuang plays a professor named Sun in it, explaining the function of horse's tail to students in rural class, but treating farmers who come to beg him as cows.

Movies:

Movies, also known as moving pictures or dynamic pictures, that is, "reflection pictures", are works in the form of visual arts, which use moving images to express ideas, stories, cognition, emotions, values, or various atmospheric simulation experiences. These images are usually accompanied by sound, and there are few other sensory stimuli. The word "film" is the abbreviation of cinematography, which is usually used to refer to film production and film industry, as well as the resulting art forms. Moving images of movies are used to create cameras that take moving pictures with actual scenes.