What are the ways of improving free writing according to elbow
​

The most affective way to improve your writing is to do free writing exercises regularly. At least three times a week. They are sometimes called "automatic writing," "babbling" or "jabbering" exercises. The idea is simply to write for ten minutes (later on, perhaps fifteen or twenty)

Explanation:

I majored in English

needs an explanation

the underlined phrase is an example of : understatment