Nothing about alcohol, true. Sitting right at the border between Sweden and Norway, the billboard displays comparative pricing for Big Macs in Norway and Sweden.
It is also important to remember that Big Macs are used as a comparison tools. The Big Mac Index is published by The Economist as an informal way of measuring the purchasing power parity (PPP) between two currencies and provides a test of the extent to which market exchange rates result in goods costing the same in different countries. It "seeks to make exchange-rate theory a bit more digestible". Source: Wikipedia
As alcohol advertising is banned in Norway similar comparison is not possible. But the message comes through anyways.