The layout container is useful when you want to build a custom display containing multiple charts as a single unit. Unlike the container, which uses tabs to cycle through charts, the layout container is a space where you are free to customize your own layout of the charts in the layout container. As the layout container offers sheet-like arrangement of visualizations, you can functionally store multiple sheets within a sheet that can be expanded for more detail.

SaaS in 60:
https://youtu.be/Z95fiVTS9Qk

Qlik Help:
https://help.qlik.com/en-US/cloud-services/Subsystems/Hub/Content/Sense_Hub/Visualizations/DashboardBundle/layout-container.htm