In WordPress, Widgets are used to add content or features to specific areas of the page. They can be found at Appearance > Widgets.
Widgets are added to specific regions, which are identified on the right of the Widgets page.
Available Widgets may be dragged into any region you like and customized as needed. Click on the widget name to open and edit.
The following image shows all regions with widgets as of 7/2020, and the widgets that occupy them.