[android] How to change an Android app's name?

Yes you can. By changing the android:label field in your application node in AndroidManifest.xml.

Note: If you have added a Splash Screen and added

<intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

to your Splash Screen, then the Launcher Icon name will be changed to the name of your Splash Screen Class name.

Please make sure that you change label:

android:label="@string/title_activity_splash_screen"

in your Splash Screen activity in your strings.xml file. It can be found in Res -> Values -> strings.xml

See more here.