pähkinänsärkijä (compound noun) –
Pähkinän is the genitive singular of pähkinä, meaning nut.
Särkijä means breaker or cracker.
In this sign, the word below (nötknappäre) is the Swedish word for nutcracker. Finland has two official languages, so you will see Swedish also on many signs.
Extra credit: In music särkijä can refer to the distortion pedal known as ”overdrive.”