Settings - Restaurant
Select the restaurant you want to configure from the dropdown in the top bar.
Then go to Settings -> General -> Restaurant.
It is important that you define correctly:
Timezone: bookings dates are all based on this timezone. It's used to calculate the time slots that are free at the front-end widget.
Language: this is the language for the dashboard only. The front-end widget can manage several languages, and the booking data will store the language on which the user made the request.
Currency: use this to define the currency symbol that will be used all over the dashboard.