You can configure the Language for the Customer Portal. If you (or admin users) have added a new language or enabled/disabled any language(s) from the Dynamics CRM side, you must sync the language data. 
When you navigate to the “Language Settings” (Portal Language Settings), you will find the Sync Language section in the first order in the language settings.
If you click on the Click Here text caption to sync the language data, you will get the successful message, But, if there is no change/update from the Dynamics CRM side for the language data, you will get the message as there is no language available to sync. 
You need to configure the following settings for the Language:
Default Language: Select the default language from the drop-down list that will contain all CRM-enabled languages. The customer portal will be displayed as per the default language selected here.
Note: Here, only those languages will appear that are configured from the CRM side.
> Manual CRM labels & content Translate
– Configure Language: Translate the customer portal content using xlsx (excel) Here, Portal admin users can translate the content by exporting an excel file and importing the translated file (excel sheet).
Select the ‘Language’ that you want to translate and Export the xlsx By opening the xlsx file, you can translate the labels & text message of the CRM into another language. 
You need to Translate all the content manually in the xlsx file.  Once the content is translated, select that xlsx file & Import it to the configured language.
After importing the translated files, you need to click on the Save button to apply the changes and update the translated content. 
> Auto Translate
Auto translation functionality is provided to translate Portal labels. You need the Google Translate API key for auto-translation.
– Google Translate: Insert the Google Translate API Key to translate the labels & content for the Customer Portal. 
Note: You must enable the “Translate API” from the Google developer console for the website domain (portal domain).
– Auto Translate: Auto translate will be only available if there is more than one language enabled from CRM else the ‘Auto Translate’ option will not appear here. 
Once you have inserted the Translate API key, you are able to Auto Translate the Portal labels by selecting the language(s).
Once you click on the ‘Auto Translate’ button, all the previous manual translations will be overridden. The language that is auto-translated will appear in the bold font style.