The properties view displays the attributes of the active object.
If you changed some properties, click the button to make the changes permanent. If you entered invalid data, a message box will show up with an error description. You can then adjust the properties and press again, or revert your changes with the button.
If you set the path to your POV-Ray user documentation in the settings dialog, you can open the POV-Ray reference page for the displayed object with the button.
You need the POV-Ray 3.1g or 3.5 HTML user documentation in order to use this feature. If your distribution does not contain this documentation you can download it here. The POV-Ray 3.5 package contains the html user documentation.
If you edit a texture or a part of a texture, you can preview it inside the properties view.
Press the button inside the properties view and a small sample scene with the selected texture will be rendered. By default the whole texture will be rendered, even if not the top item is selected. If you want to render only a part of the texture (for example a texture inside a texture map and not the whole texture map), check the local check box.