Since Valheim currently is in Early Access, and content is subject to change, there is no official PEGI, FSK/USK or ESRB rating yet. However, if the content doesn't change too much, Valheim will most likely be rated ESRB Teen and USK/FSK/PEGI 16. Probably not "kid friendly" nor USK/FSK/PEGI 12 since Valheim contains violence, blood, etc.