Tell WordPress which language file to use.
If you don’t use WordPress in your native language so far, you have to tell WordPress which language to use to activate the theme translation.
You can do this by editing the wp-config.php file (the file is located in the main directory of your WordPress files) and defining the WPLANG constant. You have to set your language code there, for example, fr_FR for the French translation.
You can do this by editing the wp-config.php file (the file is located in the main directory of your WordPress files) and defining the WPLANG constant. You have to set your language code there, for example, fr_FR for the French translation.
define ('WPLANG', 'fr_FR');
First Method: Using Loco or any other Translate Plugin
The easiest way to translate your theme locally is by using the Loco Translate plugin. After you have installed and activated the plugin, simply Go to Loco Translate > Home in the left-hand menu to start translating. You can get some guideline beginners here
Second Method: Using Poedit
Poedit is a common program which you can use to translate the theme. It’s available for free on poedit.net. After you have installed Poedit, you can open it and select File > New Catalog from POT file. Then select the .pot file from the theme you wish to translate which you can find in the /languages/ folder of the theme. Then go through every line of text and translate it to your native language. Afterwards, you can save the catalogue with your language code (for example es_ES.po). Normally Poedit automatically creates the .mo file and saves it, too. The last step you have to do is to upload your created language files to the language folder of your theme using FTP.