The layout defines the distribution of elements within the screen in sections called visual areas: Some examples of available visual areas on Studio are: Header, Content, Footer, Nav, Aside, Wrapper, etc.
A layout allows for loading sections on a screen individually, while you browse the app. Thus, it is not necessary to load a full screen if the information changes on a single area for different screens during a browsing flow.
In the example on image 6, there are 2 screens which have a layout distributed into 3 visual areas, Header, Content and Footer. When browsing from the right screen to the left screen, only the area “Contents” will be loaded since Header and Footer remain the same.