How to retrieve parameters passed by the use () method inside a function?

I am studying callbacks and I came across a method that I can not recover and I find it even simpler to send the variables into the function that is the use operator, but I do not know how to get it inside this function my_function ().

So far I have understood, the first is callback of function and second is the parameter of my_function ().

function my_function($call, array $foo) { 
    return $foo['ra'];
}


$bar = ['ra' => '853-5'];

$str = my_function(function($data) {
    return $data;
}, $bar);

var_dump($str); //string(5) "853-5"

But for me to use it this way!

$str = my_function(function($data) use ($bar) {
    return $data;
});

And not having to pass the second parameter to the function, but by the operand and use . How do I get this data passed by the use operator in my_function ()?

Thanks in advance for the answer!