What does the article category mean?

The category of an article is usually understood as the genre of the article. Generally, there are novels, essays, prose poems, operas, plays, sketches, poems, fables, fairy tales, science fiction stories, argumentative papers, discourses, narratives, letters, notices, contracts, advertisements, symposium minutes, statements, diaries, instructions, reports, summaries, abstracts, speeches, debates, briefings, briefings, prefaces, etc.