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 > Open. Then select the zionhost.pot file from the theme you wish to translate which you can find in the /languages/ folder of Zionhost theme.
Then go through every line of text and translate it to your native language. Afterwards you can save as the catalog with your language code name (for example zionhost-es_ES.po for Spanish language) File > Save as . 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 in the /languages folder of Zionhost theme and also upload those language files to wp-content/languages/themes folder using FTP/cPanel.