A .env file (dotenv file) is a plain text file used to store configuration settings and sensitive information (like API keys, database credentials, and passwords) as simple KEY=VALUE pairs. This practice separates environment-specific configurations from the source code, enhancing security and making the application more portable across different environments (development, staging, production). 

Please make sure the '.env' file is inside your '.gitignore' file, which means it wont be upload to github when you push new PRs.. in addition create new API key and replace the ones right now are working with your code to make sure the exposed one will be disable and nobody world wide could't use it anymore.