WordPress does not make this easy when you want to publish a widget to just one (or a few) pages because there is no built-in function for that kind of capability, so you have to use plugins. To show widgets on selected we recommend you to install the Jetpack Widget Visibility.
To know how to install the jetpack and its components view our tutorial about it. How To Install JetPack And Its Components
After you install the jetpack widget visibility go to the widget panel and select the widget that you want to show on selected pages. You widget panel will look like the side first image.
Click on the Visibility tab as pointed no 1 in image. After you click on it your widget will show like the right hand side widget box of the image.
You can hide/show widgets as no 2 options provide you the features.
On the right hand side widget no.3 denotes on what type of post do you want to apply the widget visibility. and no 4 detones the pages/post singularly.
No 5 will gave you options to add new settings.
