Why am i getting blank page output?

Question

The output should be a page where these are written line by line Navbar Header About Work Skills Testimonial Footer But i am getting a blank page. I have done everything instructed in the video (https://www.youtube.com/watch?v=3HNyXCPDQ7Q&list=PLaehCcszmHdyZsWhGBiz-ziLwicKZyD0W&index=1&t=1252s) from 21:23 but then also the output is invisible. The output should look like

import React from 'react';
import {About,Footer,Header,Skills,Testimonial,Work} from './containers';
import { Navbar } from './components';



const App = () => {
  return (
  <div className='app'>      
    <Navbar />
    <Header />
    <About />
    <Work />
    <Skills />
    <Testimonial />
    <Footer />
  </div>
  );
}

export default App;