Your contacts meets various kinds of forms and e-mail´s while being on your contact list´s, and these can be translated into your desired language.
You will find the translation editor under the hosted pages editor, which you can find under the menu "Lists", and select the list you want to edit.
Then choose the sub-menu "Forms".
At the right side you see the hosted pages section, choose any page and click "Edit". It doesnt matter which one, as the translations are globally on the list.
Where do i find the translation editor?
When your in the hosted pages editor, you can see a tab in the top left corner called "Translations".
In here you will see several translation options, explained below.
Here you can translate the contents of the confirmation e-mail thats sent to your contacts.
Her you can translate the contents of the unsubscribe confirmation e-mail, which is sent to your contacts when they unsubscribe.
Here you find the translations for validation messages for your form fields. You can keep the default translations or choose to make your own.
Remember to save your changes in the top right corner, when your done editing.