To support the translation of content, all strings in emails are output using the trans directive. For example,
{{trans "Thank you for your order from %store_name." store_name=$store.getFrontendName()}} {{trans "Once your package ships we will send you a tracking number."}}
The trans directive will translate strings into whatever locale is configured for the store from which the email is being sent. For example, if an email is being sent from a store view that is configured to use the fr_FR locale, the emails will be translated into French.
The directive supports multiple named parameters separated by spaces. For example,
{{trans "Dear %first_name %last_name," first_name=$first_name last_name=$last_name}}
TIP: Learn more about how translations work in Magento check documentation ↗.