Short answer
The developers listed 11 launch languages: English, French, German, Spanish (Spain), Portuguese (Brazil), Polish, Russian, Japanese, Simplified Chinese, Korean and Turkish. Italian is not in that list, although the first Graveyard Keeper had it. Check the language table on the Steam store page, since languages can be added in later patches.

Graveyard Keeper 2 promotional artwork
View full-size image ↗Official promotional artwork · © Lazy Bear Games / tinyBuild · Official media kit · Material credits
The launch language list
A developer post on the Steam community gave English, French, German, Spanish (Spain), Portuguese (Brazil), Polish, Russian, Japanese, Simplified Chinese, Korean and Turkish. Store listings show the same set.
Italian (italiano)
Italian was not announced for the sequel at launch. The original Graveyard Keeper did support it, which is why many players expect it.
If Italian matters to you, watch the patch notes and the Steam store's language table before buying.
Russian players
Russian is supported, so searches such as Reanimation Liquid or Bioreactor in Russian refer to the same items covered in our English guides.
Sources
Related pages
Official artwork · © Lazy Bear Games / tinyBuildReleaseGraveyard Keeper 2 Download
Official artwork · © Lazy Bear Games / tinyBuildReleaseGraveyard Keeper 2 Patch Notes
Official screenshot · © Lazy Bear Games / tinyBuildCraftingGraveyard Keeper 2 Reanimation Liquid
Official screenshot · © Lazy Bear Games / tinyBuildAutomationGraveyard Keeper 2 Bioreactor & Zombie Power
Official screenshot · © Lazy Bear Games / tinyBuildCommunityGraveyard Keeper 2 Voice Acting