If you open the default app you can observe that the app.js file looks like

import React from ''react'';
import { StyleSheet, Text, View } from ''react-native'';

export default class App extends React.Component {
   render() {
      return (
         <View style = {styles.container}>
            <Text>Open up App.js to start working on your app!</Text>
            <Text>Changes you make will automatically reload.</Text>
            <Text>Shake your phone to open the developer menu.</Text>
         </View>
      );
   }
}

const styles = StyleSheet.create({
   container: {
      flex: 1,
      backgroundColor: ''#fff'',
      alignItems: ''center'',
      justifyContent: ''center'',
   },
});

Output

Hello world

To display a simple message saying “Welcome to Tutorialspoint” remove the CSS part and insert the message to be printed wrapped by the <text></text> tags inside <view></view> as shown below.

import React from ''react'';
import { StyleSheet, Text, View } from ''react-native'';

export default class App extends React.Component {
   render() {
      return (
         <View>
            <Text>Welcome to Tutorialspoint</Text>
         </View>
      );
   }
}