When it comes to navigation, there are two primary types of navigation, regular navigation using Frame & Page, and navigation using modals. The key difference is the handling of the backstack and the back button—modals allow navigating the user through a "detached" flow, while Frames & Pages usually keep track of the backstack. It's important to note that modals can have their own Frame & Page backstack too, allowing for great flexibility when designing the navigation of your app.
Example user flow
For example, let's assume we have a Home Page, from which the user can navigate to a List Page. On the List Page the user is able to tweak some filters, we can show these in a modal to not disrupt the backstack/back button flow. When the user taps on a list item, we navigate to a Details Page. On the Details Page the user can view an additional Info Page in the Info Modal and navigate around further without disrupting the main backstack, once the Info Modal is closed, the user can continue navigating forwards and back in the Main Frame.