With a widget you can display additional interesting information on the Samsung Galaxy Note 9 Homescreen or call functions directly from apps.
This is very useful because you don't have to call the app first. How to add such a widget to the start screen on the Samsung Galaxy Note 9 is explained in more detail here.
1. Find a free space on the start screen of the Samsung Galaxy Note 9
2. Press and hold your finger on the free space until the screen shrinks
3. A menu appears in which you can now select "Widget"
4. Now search the list of the widget for one which you want to add to the start screen
5. Press and hold the widget until you can place it on the home screen
6. Release the widget when it is in the correct position
Proceed as follows for each widget to add it to the Samsung Galaxy Note 9 homescreen.