If it's an officially supported language, then you can purchase the pronunciation trainers and word lists from our shop, here. If you are a backer, you might still have free access to these products, so please contact us at firstname.lastname@example.org and we will get you sorted.
Keep in mind that the official application contains pronunciation training, the word lists, and the app-exclusive sentence lists.
If you're learning an unsupported language, then you'll be able to use the app once we release the “learn any language” feature. How this will work exactly is best explained here.