From WHMCS Documentation
The language files in WHMCS contain all the text strings shown to clients. This allows you to customise any of the text your clients see.
[edit] Adding Support for a New Language
If WHMCS doesn't currently have a language file for your language then you can create your own. This is a fairly simple thing to do but will take some time to translate all the text strings.
- Begin by duplicating an existing language file in the lang directory.
- Save this with the name you want shown in the language selection dropdown menu of WHMCS - it should not contain any special characters.
- Once the file is duplicated, you can begin translating all the text strings in it for your language.
- Once complete, just save and upload the file to your live WHMCS lang directory. You will then find the language available as an option in the language dropdown in the admin and client areas.
Be careful not to delete any of the quotation marks (") around the text strings or the semi-colons on the ends of each line (;). Doing so will result in errors occuring when you select your language from within WHMCS.
[edit] Modifying Existing Language Strings
You can change any of the text displayed in the WHMCS Client Area by editing the relevant language file in the lang folder of your WHMCS system. All text strings in the client area can be found in the language file and modified in any way you want.
