The following is mentioned in the node description.
To save view settings you can use the automatically created SETTINGS object. This object can be stored temporarily and will be restored, when the view is opened again. Settings will be lost, when the node is reset.
SETTINGS.mySetting = 4;
Also how is this feature helpful in KNIME web portal?.
to read and store flow variables the FLOW_VARIABLES object is used. At the moment it is not possible that a value other than the chosen default value is used after configure or execute of the node. Only when the view is opened and the changes are applied is the flow variable updated. In the WebPortal this is done implicitely when the 'Next' button is pressed.
The SETTINGS object can be used for all other values which the user wants to store temporarily. They will be saved when 'Apply' is invoked from the node view and will be restored on subsequent opens of the view. They can not be applied as new default of the node though, which means those settings are lost on reset of the node. In the WebPortal this option can be used to persist a view state after a 'Next' and 'Back' is pressed.
Hope this explanation makes the use a little clearer.