Android Package Kit is android app file extension having data and information about the app like images , text , links and version of app. Apk files are analogous to others packages like Microsoft Windows , Apple ios etc.
The Apk file is also used by developers to test the app for observing it whether in Android Emulator or Android Mobile device.
Generate Signed Apk:
Apk should be built when the project has been completed or when there is requirement of testing the app. This signed apk has unique key for the specific project in Android Studio.
For Generating the signed apk in Android Studio, Follow the steps as shown below:
1. First goto Build at top of Android Studio and click on Generate Signed apk option of Android Studio as shown :
2.Enter credentials for your app in this Dialog box shown below as:
3. Press the button named as Build apk.
4. After generating apk by android studio , the link will available in Android studio having name Show in Explorer.
5. Open the link and debug.apk named file is your APK file of App.
Problem will be discussed in Comment section.