Kalevala - the national epic of Finland, and Finnish mythology in general
Kantele - traditional musical instrument
Mämmi - traditional Easter food
Kalakukko - traditional Savonian food
Karelian pasties - traditional pasties from the region of Karelia. “Karjalan piirakat”
Sauna - traditional hot room
Sisu - will, determination, perseverance, mental fortitude, also a Finish pastil
Perkele - swear word (see Finnish profanity) also god of thunder in Finish mythology
Puukko - traditional Finnish style woodcraft belt-knife
Ice swimming - swimming in a body of water with a frozen crust of ice
Nordic walking - a recreational sport first popularized in Finland, you walk with sking sticks
Salmiakki - salty liquorice
Sahti - traditional homemade alcoholic drink
Koskenkorva - strong Finnish vodka
Reilu meininki - fair dealing very rare in Finland :)