Google Assistant is available in a few different forms, one of the more popular forms is through Allo, Google's messaging app. And now, the Google Assistant has learned Spanish and French Canadian (not to be confused with French spoken in France). However these languages are only available in the Allo messaging app. They aren't available on Google Home, or in the regular Google Assistant - which is found by long-pressing your home button - yet. They will likely come to those other forms of the Google Assistant in the near future, but this shows just how fragmented Google Assistant is, already.
To enable French Canadian (or Spanish), Google has made it really simple. You just have to say "Google, speak to me in French Canadian", which is very easy, and much better than having to go into the settings and change the setting to make this work. The same works for Spanish as well. Once you utter that phrase, Allo will take care of the rest and talk to you in French Canadian or Spanish. Now, if you are a bilingual user, and use both English and Spanish or French Canadian at the same time on your smartphone, Google Assistant can still keep up. Assistant will be able to give you the appropriate response, based on the language the question or phrase is stated in.
When Google Assistant launched last year, it was only available in English (US). That is typically how these things go, starting as US only and then expanding outside of the US and Google Assistant was no different. It is a bit interesting to see these two languages as the second step for the Google Assistant, but it is definitely nice to see. There's currently no word on what the next languages will be, for Google Assistant, and there's also no word on when Spanish and French Canadian will make its way to other versions of the Google Assistant. Google will likely be giving everyone an update on the Assistant at Google I/O next year and perhaps offer up some information on what will be coming to the Google Assistant in the very near future.