That's a fully functional flashcard application for Udacity's React nanodegree program, where the user is able to create Decks containing Cards with Q&A and answer them later.
In the project directory, you can one of the options below:
npm install
yarn install
and then (also one of the following):
npm start
yarn start
Finally, open the Expo Client application in your Android smartphone which can be downloaded here. The Application will be built and then it will start.