An emulator is a program that mimics one kind of hardware while running on a different kind of hardware. With the Android emulator, you can create a virtual version of just about any tablet, phone, or wearable right on your desktop.
To run your Android program, select Run > Run ’app’ or click the Run button on the toolbar:
In a few moments the Choose Device window will open:
Verify that “Launch emulator” is selected and that the name of an Android virtual device (AVD) has been filled in. Click OK to run it.