can anyone pls tell me what is the purpose of get browser data, set browser data and invoke activityX method under UI automation activity
What version of UiPath are you using?
The ActiveX activity is meant to be used with a deprecated ActiveX technology created by Microsoft. It worked best on IE, which by itself is going to be soon phased out.
The other activity is the Set Web Attribute that sets a certain HTML attribute of a browser page .
The converse of that is the Get Attribute. There is an example in the documentation that shows how to use it