Background :
Basically in Sitecore projects, usually we need to create a new language for items. For some languages, we just need to copy the same content from an existing language.
For example, copy content from en to en-GB languages.
Is it possible to do this in Sitecore out of the box ?
Yes, Sitecore OOTB provide a translation module under versions tab as below.

What is missing in the Sitecore Translation Module ?
It is not possible to translate an item with descendants, you should translate item by item. When you have a large number of items to translate, it can be long and not practical.

Solution : Use the module Sitecore Powershell Extension !
In this post, we will use SPE, for those how don’t know the Sitecore Powershell Extensions, please take a look to the website of the module hear.
In Sitecore, in the desktop mode, go to PowerShell ISE in Development Tools as below :

Copy and paste the powershell script below in the editor and run :
You should select the location of the item parent for translation as below :

Enjoy 🙂