For version from 2.5.0
Please copy the file:
/app/locale/en_US/WP_OnePageCheckout.csv
to
/app/locale/[your locale]/WP_OnePageCheckout.csv
Then open to edit /app/locale/[your locale]/WP_OnePageCheckout.csv. You need to change it to: "EnglishName","[[EnglishName in your language]]"
For version lower 2.5.0
1 Please download WP_OnePageCheckout.csv
2 Open to edit /app/locale/en_US/WP_OnePageCheckout.csv.
You need to change it to: "EnglishName","[[EnglishName in your language]]"
3 Open /app/design/frontend/[your package]/[your theme]/locale/en_US/translate.csv, and add the contents of a WP_OnePageCheckout.csv to the end of translate.csv file.
Note that file encoding should be UTF8. We recommend Geany
Language csv-files Generator
Extract your module's strings to translate directly from your .php and .phtml file and generate the language .csv file easily: Language csv-files Generator
Reduce checkout process from 6 steps to 1 with fully responsive OnePage Magento Checkout extension. Supports AJAX-updating of totals, Payment methods, Shipping methods, shipping rates and much more.