Hello Kavya , Based on my knowledge, surface automation means… automating any application with out knowing the object properties. example: reading text on citrix environment and clicking on the object based on text. in this example citrix environment is secured by VPN. So application will be visible but no object properties will get disclosed by secure VPN layer. In this condition it is very difficult to create a selector to recognize the object. This is called surface automation. It depends more on clicks based on text and pixel of the screen and location.
Hope my inputs are useful.