Jila is a framework for building simple language learning apps. This particular repository is for the administrative backend and the API used to communicate with the app.
The Jila backend is written using Ruby on Rails and the ActiveAdmin framework to make it easier to get things up and running. See their documentation if you have any particular questions.
The backend is a fairly vanilla Ruby on Rails application, so hosting arrangements can be whatever suits the user. The team have been using Heroku for both development/testing and production environments. Asset storage (images and audio) is configured to use Amazon Simple Storage Service (S3) for production-like environments, and the local file system for development.
The production environment uses Paperclip to upload the assets to S3. For each deployment environment you will have to set environment variables for the S3 bucket name, and the credentials, as outlined in production.rb.