"Hentai" is a Japanese term that refers to explicit adult anime or manga content. In English, it generally means "pervert," but in the context of adult anime/manga, it specifically indicates erotic or pornographic material.
"Petite" simply means small or tiny, often describing someone who is physically small or young-looking. In a porn context, it can refer to a smaller physical stature, such as petite women being of smaller stature than average.
So, combining these two terms, "hentai-petite" would describe explicit adult anime or manga content featuring smaller and younger-looking characters.