Beer cases are items that can be purchased from Teimo's Shop for 745mk per case. The beer from the case decreases/increases stats by the same amount as beer bottles. 7 beer cases has 168 bottles in it.
The brand of the beer is Nivalan Kalia ("Nivala's beer", Nivala being a municipality in the Northern Ostrobothnia region). It's likely a parody of the real Finnish beer brand Olvi, that is based in the nearby municipality of Iisalmi. Another brand of beer, Kurjala, is also mentioned by Jani, the driver of the yellow car, but cannot be purchased by the player.