usort()関数

// setting data
$arr = [
    ['name']=>'Kan', 'point'=>4],
    ['name']=>'Kenji', 'point'=>5],
    ['name']=>'Akai', 'point'=>3],
    ['name']=>'Genta', 'point'=>4],
    ['name']=>'Shizuka', 'point'=>8],
    ];
    $point_cmp = function ($a, $b) {
        return ($a['point'] < $b['point']) ? -1 : 1;
    };

    usort($arr, $point_cmp);
    //result
    foreach ($arr as $u) {
    echo $u['name'].":".$u['point']."\n";
    }