Open Extension Management and check if extension named 'Estonian language for Estonia' is installed. If not, please contact your partner.
To change application language into Estonian, open My Settings, and choose 'Estonian (Estonia)' for the Language.
To display dates and numbers according to Estonian format, choose also 'Estonian (Estonia)' for the Region.
Click OK to apply and close My Settings.
You should see now Dynamics 365 Business Central in Estonian.
For more information, please contact one of the partners: