I checked the site, I checked Github, but I still have no idea what "ORM" means.
Wikipedia suggests several different meanings which seem to fit: Object-relational mapping, Object role modeling, Online Reputation Management, Online research methods, Outsourcing Relationship Management
Put as simply as I can put it, it's an abstraction layer in front of SQL.
The general logic (which I object to, though I still prefer ORM-based development) is that most of your class Objects relate to how you would store them in a database. Your 'User' object has a first name, a last name, a password, etc., which all map neatly to database records.
So, instead of doing "INSERT INTO users firstname, lastname, password) VALUES ('foo', 'bar', 'baz');", you create a user object:
Wikipedia suggests several different meanings which seem to fit: Object-relational mapping, Object role modeling, Online Reputation Management, Online research methods, Outsourcing Relationship Management