* Her favorite genre is science fiction. (This uses "genre" as a noun, specifying a category of literature.)
* The film transcends its genre with its unique storytelling. (Here, "genre" is a noun referring to a category of film.)
* Many critics argue that the novel doesn't fit neatly into any single genre. (Again, "genre" is a noun, this time plural, referring to categories of novels.)
* We need to consider the genre conventions before we start writing the screenplay. (Here "genre" functions as a noun, referring to the typical characteristics of a particular category.)
The word "genre" is always a noun. You'll usually use it to talk about categories of creative works, such as literature, music, film, or video games.