readLine() what does this do in this code

x = (score) => {
score = parseInt(readLine(), 10)
return score >= 88 ? "excellent" : (score <= 87 && score >=40) ? "good": "fail";    
}
console.log(x())

x = (score) => {
score = parseInt(readLine(), 10)
return score >= 88 ? "excellent" : (score <= 87 && score >=40) ? "good": "fail";    
}
console.log(x())