Their progress should display like the rest of the class - that said, let us know if you're finding that it's not working that way.  Just double check that they're logged in to the site as expected and all should be good!

Thanks. Does that mean that they will be using the same account, if they go to, for example, Khan Academy Lite or the espagnol KA?

Khan Academy Lite is a separate entity from our organization, so accounts would not be transferrable across those products.  

But if you just go to https://es.khanacademy.org/ (which is just a translated / localized version of our main site) the progress will be saved the same for the original account, which may have already done some work in English.  You can double check with your own account to get a better sense of the dual experiences.