For questions about the web interface of Google's note-taking app, Google Keep. Questions about the Android app should go to android.stackexchange.com.
Launched March 20, 2013, Google Keep is a note organization service tied to Google Drive.
Designed to work with a companion Android app, Google Keep allows the user to quickly create notes and task lists. It also allow for voice transcription of notes for even more convenience and also can store photos to go with a note. And, of course, the ability to search for notes is deeply ingrained into the service.
If your question is about the Android app, you may find the answer to your question at Android Enthusiasts.