The game is now localized to 26 languages (plus 3 variants) that have full platform support on Steam: https://partner.steamgames.com/doc/store/localization/languages
When you start the game, if you didn't choose a language yet, the game shows a screen to choose a language from.
Language can also be changed in Settings.
There's only English Steam page at this point, going to add localized Steam pages soon.
I expect to add more languages after full release of the game.