Nearly all Mac users run OS X in their primary language and mother tongue, but for polyglots and those aiming to be bilingual or trilingual, adding multiple new languages to Mac OS X can have obvious benefits. We’ll show you how to add a new language and how to change to that new language, which will impact how things appear and read on the Mac.
Adding a new language doesn’t remove the prior language, it becomes an additional option. In fact, you’ll have the ability to easily switch between the languages and set one or the other as a primary language at any time, and change between them as needed. Something else to keep in mind is that when you switch the language on a Mac, many things change with it, from menu items, to date format, measurements, and assorted other items through the system – these can all be adjusted individually if desired, but for our purposes in this tutorial we’re going to focus on adding and changing the language in Mac OS X.
You can add as many languages as you want, but in this walkthrough we’ll focus on just adding a second new language and changing to that as the new language default.
That’s all there is to it, easy enough. If you set the new language as your primary language, menu items will refresh, but if you want everything to switch over to your new language choice then you should log out or reboot the Mac so that applications refresh to the new language selection as well.
If you are actually going to use the secondary language full time or you are aiming to improve your proficiency, learning the keystrokes to change the keyboard language can be very advantageous, and adding an accompanying voice to the Mac can be beneficial as well.
By the way, if you’re looking to add multiple new languages that you can switch from, use the typical multiple-selection tools in Mac OS X to choose a few at a time. For example, holding down the Command key and clicking selections allows you to pick two noncontiguous language selections to add:
While this is primarily aimed at those who speak and read multiple languages to begin with, it can also be very useful for people looking to improve their fluency in another language. For example, I have a friend who is becoming conversationally fluent in Spanish, and adding (and switching between) the language to daily computing use has further helped along that process.
CR : http://osxdaily.com/2016/04/26/add-change-language-mac-os-x/