Please navigate to Admin > Account > Helpdesk Settings , and change the primary language of your product portal.
We support multiple languages from the Pro plan which can also be managed under helpdesk settings. Once you set up secondary languages, the primary language of the portal will be locked.
Feel free to reach out to support@freshdesk.com in case you are looking to manage the primary language after setting up secondary languages.
To see the complete list of languages supported by Freshdesk, click here.