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So, what kind of stuff do you write?

You would expect him to use conventional nouns: "Oh I write books, or I write newspaper articles."

This person is trying to make up a name to describe their writing. Like giving a book a title, or naming a child. He's inventing a term to describe what his work is like..... "I guess you could call it instructional" If he was writing cook books. He's describing what he thinks his writing is about or reflects. He thinks his writings most obvious or unique characteristic is that it typifies or expresses the ideas of "an angry young man" so he feels you could call it "angry young man" writings.

A book that expresses English grammar, is an English Grammar book, right? He's making up his own word to describe what his book is. It's like naming a child. He's naming his writings, like you would name your first child, or how your family has a last name. He's making "angry young man" the 'last name' of his writings. His writings belong to the "angry young man" family. Or do you want to know what "an angry young man" is? It's a ARCHETYPE or stock character.

http://en.wikipedia.org/wiki/Angry_young_man

"Angry young man" describes a 1950's male style of writing regarding their discontentment about life.