what is the use of an Creative Activity?

I think you are a little bit confused or am I? I don't know what is creative activity but there is a component of Android OS named "Activity". According to developer.android.com,

"The Activity class is a crucial component of an Android app, and the way activities are launched and put together is a fundamental part of the platform's application model. Unlike programming paradigms in which apps are launched with a main() method, the Android system initiates code in an Activity instance by invoking specific callback methods that correspond to specific stages of its lifecycle."

You can find more information about activities here,
https://developer.android.com/guide/components/activities/intro-activities