Android Studio doesn't do anything unique to build your application; it calls Gradle to perform the build the same way you'd call it from the command line.
However, Studio runs a synchronization process when you open your project (or explicitly ask to synchronize). Studio analyzes the build files to determine the project structure and index dependencies, allowing Studio to provide features such as code completion and launchers to run your application.
For details on running and debugging your application, see Run and debug your app.