Layered architecture, is an architecture pattern that helps for having a more organized and structured codebase.
Each layer has its distinct job and all the layers communicate via well-defined interfaces.
This architecture helps us with maintainability and scalability and is often used on enterprise applications.
You should be strict about not letting these layers have direct dependencies with each other, otherwise, you will lose the benefits of this architectural style.
Usually, the communication or interaction between layers is top-down at higher levels of the application such as user interaction using lower parts of the application such as the Database.
The key idea of this architectural style is to have a clear separation of concerns.