The JSON Page View is used when the page type of a Window is JSON. The view is almost identical to the XML Page View, except that it show JSON and not XML in an expandable tree. It is split into several sub views, as shown below: the Address Bar, the JSON Path View and the JSON View.
The JSON Page View may show JSON loaded in two different ways: from an URL (e.g. as the result of executing a Load Page Step Action or as the response from a web service call) or from an JSON variable. If the JSON is loaded from an URL it is read-only and can therefore not be modified. If the JSON is loaded from a variable it is essentially a view on that variable and any modification of the text in the view is reflected in the value of the variable.
The Address Bar show the URL of the JSON in the Page View. You can also (like in a browser) enter a new URL in this and if you press Enter a new Load Page step will be inserted in the robot before the current step. The Address Bar is only present for JSON loaded from an URL and not when it is from a variable.
In almost all other aspects the JSON Page View works like the XML Page View, you can left-click to select, you right-click to to configure and insert new steps and the functionality of the toolbar buttons is the same. The options available in the right-click menu is selected such that these are relevant for JSON and if an option is shown, but is not enabled it means that it cannot be used with the given selection, e.g. Extract Property Name is only enabled if the selection is a property declaration (name/value pair).