'Hei' is the standard informal greeting in Finnish, equivalent to 'Hi' or 'Hello' in English. Finnish is a Finno-Ugric language unrelated to the Germanic languages. Swedish uses 'Hej' (pronounced similarly but spelled differently), Scottish Gaelic uses 'Halò', and Irish uses 'Dia dhuit' for formal greetings or various informal options. This question tests basic vocabulary knowledge of European languages, specifically distinguishing Finnish from its Nordic neighbors who speak Germanic languages.