react-i18n

Steps

npm install react-i18next i18next --save

Add locales folder with en.json and index.js

In any component like app.js

import './locales/index';
import { useTranslation } from 'react-i18next';

Add above return

const { t } = useTranslation();

In render return

 <p>{t('dummyNamespace.medium')}</p>

dummyNamespace json need to add in all json file as per your module