Pizza Co. has written words that appear on the screen, and those will be in the language of your tablet. The spoken language of the characters is not a real language, it's make-believe. We plan to reveal more about this make-believe language in the near future.
If you find the 'Osmolian' language distracting, please feel free to lower the volume accordingly.
Note that Osmo is currently available in the following languages:
English, Chinese (Traditional and Simplified), Danish, Dutch, French, German, Italian, Japanese, Norwegian, Spanish and Swedish.
To switch Osmo interface messages to a language other than English, you need to change the language setting on your tablet.
Here are the instructions from the Apple website:
If you're using an Amazon Fire tablet, open your Settings, and search for 'language' (options you need to select depend on your tablet model).
After you do that, open any Osmo app, and you will be prompted to select between English and your other language as the preferred language for that Osmo app.