WordPress widgets add content to the sidebar on your page. Examples are box, figure, embed video, recent posts, text, link list, etc.

To add a widget to your pages:

1. Go to Appearance > Widgets. You will see available widgets on the left and widget areas on the right (blog and page).
2. Click on one of the available widgets and drag and drop it under the Page sidebar (if you want the widget to be displayed on your blog – under the Blog sidebar).
3. After dropping the widget, the settings will be displayed. Fill in the fields to add content to your widget. 
4. Click the Save button at the bottom.

To add a widget only to one particular page

1. Follow the above steps.
2. In the last fieldset select Show on checked pages.
3. Navigate to the Post Types tab.
4. Check a box with a page or pages where you want the widget to be displayed.
5. Click the Save button at the bottom.

To delete a widget click on the Delete link at the bottom of the widget settings.