Languages: the dashboard, the Secretary and your customers
Set the dashboard language, and understand how the Secretary decides which language to reply in.
The dashboard
Under Profile → Preferences → Language & Region, choose the language you want the dashboard in. English, Spanish, French, Arabic, Hindi and Chinese are available. The choice is saved to your account, so it follows you across devices.
The Secretary with customers
The Secretary replies in the language the customer writes in. A customer who writes in French gets French; one who switches mid-conversation is followed. You do not need to translate your knowledge base; the Secretary reads it in whatever language you wrote it and answers in the customer's.
If you want to force one language for every reply regardless of the customer, say so in the knowledge base ("Always reply in English").
The Secretary with you
Your own Secretary in Secretary → Chat uses your dashboard language.
Confirmations and reminders
Booking confirmations, reminders and receipts go out in the language of the conversation they came from.