What’s react-bootstrap and How to use it?

import React from "react";
// react bootstrap componentimport Card from 'react-bootstrap/Card'
import CardDeck from 'react-bootstrap/CardDeck'
import Button from 'react-bootstrap/Button'//  import bootstrap css file here
import 'bootstrap/dist/css/bootstrap.min.css';//  import bootstrap sass file on style.css
// https://getbootstrap.com/docs/4.4/getting-started/theming/#sass
// @import "../node_modules/bootstrap/scss/bootstrap";import "./styles.css";export default function App() {
return (
<CardDeck>
<Card className="card">
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</Card.Text>
</Card.Body>
<Card.Footer>
<Button> Read me </Button>
</Card.Footer>
</Card><Card>
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This card has supporting text below as a natural lead-in to additional content.
</Card.Text>
</Card.Body>
<Card.Footer>
<Button> Read me </Button>
</Card.Footer>
</Card><Card>
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to additional content. This card has even longer content than the first to show that equal height action.
</Card.Text>
</Card.Body>
<Card.Footer>
<Button> Read me </Button>
</Card.Footer>
</Card>
</CardDeck>
);
}