React Project - Invalid environment variables: { DATABASE_URL: [ 'Required' ] }

Hello guys! I hope you're all well. I'm not a full-stack dev, but one day who knows? So, I've cloned a React project to work on it! I installed the modules, etc, but unfortunately, when I type the command in my terminal - npm run dev- I get some errors. I'm searching tutorials, docs e, and so on and so fort, but I did not get successful. Please, someone could please help me to find a solution to this trouble. Description ERROR bellow. Thanks in advance.