This action is used to set various types of properties on a component. This is a ONETIME action. If you want something that will constrain a property to a value use the Constrain Property action
When setting properties of a Point type like the position or velocity property on a spatial it is important to set the whole point value instead of accessing the X or Y value. A Point property can be set using the Point property type of this action or via the setPoint() helper method in an expression.
Setting a property via an Expression Reference allows for calculations to be made before the property is set. Setting a property with a Property Reference is more performant than using an Expression. If you want to concatenate / construct a String value using an expression make sure to surround the explicit String value with quotations (").
Setting a property via a Property Reference is pretty straight forward. The "Pass Value of Reference" checkbox should be checked if you want the value of the property being referenced to be used. Leave it unchecked if you want to pass the String value of the property reference address.
Flash converts color values to a uint number so to make it easier just use the Color type and open the popup chooser to select a color or provide a Hex value and it will be converted for you at runtime.
All other values whether its a String or Number can be chosen here as well.