This great feature can simplify the editing of long documents on a single monitor.
With your document open, click on “View” to show this ribbon and then click on the button on the right called “Split”:-
As you can see below, Word places a line across the middle of your screen. It also adds separate scroll bars – 1 for the top pane and another for the bottom pane:-
You can now use the scroll bars to move up or down either pane. Alternatively (provided you have the selection point in one of them), you can use the Up/Down or PageUp/Page Down keys on your keyboard to move up or down the pages.
If you want to go back to a single pane for the document, simply click on “Remove Split” on the right of the “View” ribbon