View Height quite simply enables you to determine a fixed height for the 'View'. The word 'View' is used to define the specific tile. Therefore, you can simply consider the height to be equivalent to the height of a specific row, not the total height of the Widget.
If the widget was a Slider, the View Height would be the full height of the widget. However, if the widget was a Grid with 4 rows, the View Height would be the height of one row.
Common use cases are to change the dimensions of the widget, for example: