Klaviyo does not currently have a built-in feature that automatically translates email content into different languages. However, if you want to configure email templates in a variety of languages, they will certainly be supported in Klaviyo. Klaviyo allows full customization and translation of all email content and in-email tags (unsubscribe links, manage preferences, etc).
You can also configure email templates that will show/hide certain blocks based on a property about the recipient. Let's say, for example, you have customers in the U.S and in Germany. You can configure a single email template to only show German content for recipients located in Germany and then have English content for all U.S. based customers. Given this, there's no need to have separate Klaviyo accounts for each language.
Segmenting/Targeting Based on Language Preference
In order to segment your contacts and send emails in different languages, data regarding each contact's language preference must be stored in Klaviyo.
You can, for example, add a required Language Preference question to all of your newsletter sign-up forms in order to ensure you collect this information for all subscribers.
Unfortunately, Klaviyo will not be able to automatically detect language preference based on the language a customer was using on your website. We do automatically assign all contacts in your Klaviyo account an estimated location based on IP Geolocation; while this is not a perfect science, despite being an industry standard, it will allow you to segment different sends based on this location if you wanted to infer language preference based on geographical location.
Changing Sign Up Form Opt-In Text
If you are using a Klaviyo sign up form, you might want to change the text that shows at different stages of the subscriber process. You can adjust this text by first navigating to the list to which your form is linked. Next, click Subscribe Pages across the top and then click the bright blue View All Pages link. Here, you will find the following pages related to your list's subscription process:
If you click on any of these pages, you will be able to adjust most text to any language you'd like!
At the moment, the double opt-in confirmation pages contain a block of text and an unsubscribe button that can't be translated (namely the unsubscribe confirmation page). Email confirmation can be turned off, however, to make a list single opt-in for paid accounts. Email email@example.com to request a list be set to single opt-in.