What is decorator

After a lot of time working with angular, I suddenly found myself wondering: What exactly this syntax (like here):

@Component({
  selector: 'kinder-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.scss']
})
export class LoginComponent {
  showFeddback = false;
}

(which I use so lot of times) means?
In other words: what is exactly decorator?
According to angularjs docs:
Decorators are a design pattern that is used to separate modification or decoration of a class without modifying the original source code Which means: after you create some class - the decorator adds some additional functionality to it.
I decided to to experiment with creating my own decorator (to see how it feels to write decorator):

import { Component } from '@angular/core';
export function Vasia() {  
     console.log(`hhh!!!!`)   
}
@Vasia()
@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  name = 'Beautifull Girl';
}

Now each time you refresh the page - you will see 'stay with me!!!!' output in the console