What exactly does the while loop do here in insertion sort?

function insertionSort(arr)
{
    // Two loops, outer to look at each element, and inner to shift elements

    // Outer loop
    for (let i = 1; i < arr.length; i++) // i starts at 1 because we don't need to sort the first element
    {
        let key = arr[i];
        let j = i - 1;

        // Inner loop
        while (j >= 0 && arr[j] > key)
        {
            arr[j + 1] = arr[j];
            j--;
        }
        arr[j + 1] = key;
    }
}

const arr = [8, 20, -2, 4, -6];
insertionSort(arr);
console.log(arr); // [-6, -2, 4, 8, 20]

It’s working fine I just don’t understand it and I can implement it all on my own except for the while loop. I’m a beginner so please bear with me