Receive the event handler: calling method from parent component

In the ‘Stateless Components From Stateful Components’ section, in Child.js line 11

this.props.onChange(name);

Why is it ok to use prop onChange like a function and pass in parameter here? Is there no direct way to call a method changeName from parent function in child function? Is it because after defining the prop onChange to trigger changeName function, onChange can be used as a function?