The maps element declares that applications will use platform maps service. This element contains information about GoogleMapsAPIKey for Android and will automatically add the corresponding permissions for WindowsPhone.

<maps androidGoogleMapsAPIKey="AIzaSyBxODbx_HT_Yojw1RfVkSO6uZrwWcGsbvY" />

For Android, an AndroidGoogleMapsAPIKey is required to enable the application to display maps. Follow the steps explained in this Android documentation to generate this special key.