Ensure .env is listed in your .gitignore file so it never ends up in a public repository.
Developed by Eugene Roshal, RAR is a proprietary archive file format. It is used to "wrap" the .env file (and often other project files) into a single, smaller package to make it easier to transfer or store. Why Developers Use "Env" Archives Download Env rar
To understand what you are downloading, it helps to break the term down: Ensure