how to change woocommerce language?

WooCommerce comes localization ready out of the box – all that’s needed is your translation, if the plugin does not come bundled with one for your language.
There are several methods to create a translation, most of which are outlined in the WordPress Codex. However, we find the easiest method is to use a plugin called Loco Translate. More advanced users can use PoEdit. Both methods are covered in this doc.

Before you begin 

WooCommerce includes a language file (.po or .pot file) which contains all of the English text. You can find this language file inside the plugin folder in woocommerce/i18n/languages/.

Set up WordPress

WordPress needs to be told which language it should run under.

1. Go to: Dashboard > Settings > General and change the Site language.

Once this has been done, the shop will be displayed in your locale if the language file exists. Otherwise you need to create the language files (process explained below).

WooCommerce 2.2+ Language Packs 

From version 2.2, WooCommerce includes a language pack downloader. PO and MO files will no longer be bundled with the plugin – they will be downloadable from your dashboard if you have the WPLANG constant set, or from a git repository if you wish to grab them manually. A notice will be displayed within your administration:

Update WooCommerce 2.2+ Translation Packs

If for some reason the translation packs install fails, you can force the download in WooCommerce > System Status > Tools > Force Translation Upgrade:

Force Translation Upgrade (WooCommerce > System Status > Tools)

PO and MO files are copied in wp-content/languages/woocommerce/