The BusyLabel is a is a non-interactive display that shows a spinning circle and a label describing the busy state. The BusyLabel is provided for convenience for implementing platform-style full-screen busy indications, and doesn't need to be explicitly positioned.
For example, it could be used while a page is loading its contents:
If you don't want to show label use PageBusyIndicator instead, for cases when the reason of loading is obvious from the context, the busy state is too short to read descriptions or displaying additional label would feel like a clutter.
If a more custom solution is needed use components BusyIndicator and Label directly instead. One common custom case is to provide horizontally centered "Cancel" button below the loading indication, especially if the loading can take really long time.