Question operator in PHP object syntax

I want to know what it is that in PHP object syntax:

        public function myMethod($data) {
            foreach ($data as $attribute => $value)
                [B]$method[/B] = 'set'.ucfirst($attribute);

                if (is_callable(array($this, $method)))
                    [B]$this->$method($value); [/B]

So I wonder what is the syntax $ this->$ method
Why not do the same without the operator $ this->.
What are the advantages of this syntax?

Can you explain?
thank you

Did you try doing it without the $this-> ?

$this-> , inside class body, refers to the current object of that class, it makes the difference between property of the class and simple variable, class methods and functions.