This is a Text-To-Speech (TTS) engine for the Klingon language to be used in conjunction with {boQwI'} or Duolingo.

To use with Duolingo use any browser which supports the text selection action and request the desktop site. (Chrome supports this Firefox does not.)

*** Note: This is NOT AN APP itself. ***

A Text-To-Speech engine is a system component that works in conjunction with apps that want to produce spoken output. For an example of an app which can speak Klingon see {boQwI'}:
https://play.google.com/store/apps/details?id=org.tlhInganHol.android.klingonassistant

Any app can produce Klingon speech output through this TTS engine by calling Android's TTS API using a locale with language code "tlh". See this documentation:
http://developer.android.com/reference/android/speech/tts/TextToSpeech.html

Once again THIS IS NOT AN APP. If you leave a comment that you "can't open it" you are basically saying that you don't understand what this is.