This is a Sonic 'play a sound' type book. A similar one was released in England, but this one is for Finland and is all written in Finnish so kids can understand. Probably the sounds are the same, because they weren't ever words. It runs on batteries and has thick card type pages. You push the button when certain cues come up in the story or game. While the other books like this were basic play a sound books, this one claims to be a game book with randomizer. The water soluble pen would probably write on the card-type pages for activites, & wipe off later. With randomized lights/sounds you could play the games over & over.
The little starburst says "7 Etektronista Pella" which is '7 electronic games' & then the button says "Paina" (which means push). The other things are Vesiliukoinen kyna (Water soluble pen) and Sattumoittaja (randomizer).
It's great to see Sonic books were translated into at least a few languages, so everyone can enjoy them!