na-adjective, noun which may take the genitive case particle 'no', noun
popular; common; accessible to the masses
Describes something that is easy for ordinary people to understand or enjoy, often with a nuance of being simplified or not too academic. Commonly used in contexts like 通俗文学 (popular literature) or 通俗的な説明 (a layperson-friendly explanation).
この本は難しい哲学を通俗的に解説している。
This book explains difficult philosophy in a popular, accessible way.
彼は通俗小説を
He writes a lot of popular novels.
Compound of 通 (つう, 'pass through, common') and 俗 (ぞく, 'customs, vulgar'). The combination conveys the idea of something that is common or accessible to ordinary people.