Poedit is a software which you can use to translate language of your plugin content or theme. ‘English(United States)’ is default language for wordpress but you can change its language easily in following steps. Here is complete list of Languages Codes and Country Codes.

Change language of your plugin content

Step 1To change languages of your plugin contents , we use poedit software.
Step 2 Open Poedit and click on “File/Open…” and Select the .POT file or the .PO file from the plugin you wish to translate which (you can find the files in the wp-content/your-plugin-path/language/ folder).
Step 3Now you have to change the language file for your language.Then go to catalog menu-> Properties file.
 
Catalog Property
Step 4A box will pop up asking for language of the translation. Select your language and click ok.
 
Language select
Step 5Now you can start translating your plugin content- just go through every line of text and translate it to your native language.
 
Translated File
Step 6When you’ve finised save your file with your language code (for example de_DE.po). Poedit will automatically create both .po and .mo files.
Step 7Upload the file to your /languages folder : Below is screenshot of .po and .mo files for German languages. Upload your files to the languages folder you just created. For e.g ‘wp-content/your-plugin-path/languages or lang’ folder.
 
Language
Step 8Change the language in the admin settings : Then switch your wordpress dashboard and go to Settings -> General -> “Site Language” setting.
Step 9Select the language option corresponding to the .mo file you just uploaded and click on Save Changes.
Step 10Refresh your page and you should see your plugin contents in German language.
 
PO File Frontend