What is Polylang?
Polylang allows you to create a bilingual or multilingual WordPress site. You write posts, pages and create categories and post tags as usual, and then define the language for each of them. The translation of a post, whether it is in the default language or not, is optional.
— Polylang — WordPress plugin | WordPress.org
How to install and set up
Start WordPress and login to WordPress Dashboard
Start WordPress from Shifter Dashboard

Login to WordPress Dashboard by clicking [Dashboard] button

Navigate to Plugins menu, then click [Add New]

Search “Polylang” and click [Install Now] button

Activate it.

Setting up Polylang plugin
Click [Settings]

Complete initial setup

We install Japanese as a sub secondary language.

Media

Set English is primary, Japanese secondary in this sample.

You’re almost ready

Scroll down to the bottom of page, click [Return to the Dashboard]

Check the language installed

Check URL modifications
Navigate to [Settings] menu

Click [Settings] under URL modifications

URL modifications
Keep all settings default.

Set Language Switcher to theme’s widget
Navigate to Appearance to Widget

Make sure Language Switcher is added to Blog’s sidebar

Make some posts and publish
Add some posts in both languages.

Stop WordPress and generate an artifact to check ‘Language Switcher” works.

That’s all