Widgets are mini-apps (e.g., weather, clock, calendar, etc.) that can be added to a Home screen. They aren't the same as shortcuts as they generally display info and take up more space than a single icon.
From a Home screen, touch and hold any open space (where no shortcuts or widgets are present).
From the Widgets tab, select a widget.
For the widget to be successfully added, there must be sufficient space on the screen.
To move the widget, tap and hold then drag to the preferred location.