In Notion, pages can house other pages. You can see nested pages by clicking the dropdown on any page in your sidebar.
All content in Notion, lives on a page.
To tell where a page lives, you can look at the breadcrumbs at the top of the page.
We recommend having a company operating systems page and a page in the sidebar for every major function on your team.
Like marketing, design, or engineering. Within those pages, you can further categorize as needed.