You have to return a valid response from the component. For example, if you want to make a Component using FlatGrid you can use this structure:

import { View } from 'react-native';
import { FlatGrid } from 'react-native-super-grid';


export default function Example() {
  return(  
    <View>
      <FlatGrid
        itemDimension={130}
        data={[1,2,3,4,5,6]}
        renderItem={({ item }) => (<Text>{item}</Text>)}
      />
    </View>
  )
}

And also I see you are using a class class named Grid that is extending the React.Component () and from your code I see you are not importing the React from react so in order to use the class you have to use:

import React from 'react';
import { View } from 'react-native';
import { FlatGrid } from 'react-native-super-grid';

export default class Grid extends React.Compoment {
  render(){
    return(
      <View>
        <FlatGrid
          itemDimension={130}
          data={[1,2,3,4,5,6]}
          renderItem={({ item }) => (<Text>{item}</Text>)}
        />
      </View>
    )
  }
}