It is just like you would expect out of something like this. Your free to go wherever you want, at least once after you've finished the "training mission" and acquired your father's sword and shield. From that point on in the game, you can sit in a boat and go to any of the neighboring tiles in search of the four items required to defeat the Oceanhorn.
To do this, you will be exploring a lot of dungeons, battling all different sorts of enemies, solving puzzles is your progress, interacting with the world around you and exploiting its somewhat limited but still pretty fun physics system as well as cutting all of the grass grass and smashing every single pot that you run into because it just might a gold piece!
The games top-down and very vertical so most of the time you will be figuring out how to climb to the higher points of an island to get to a treasure chest or simply for the sake of exploration.
The best that I that I can give you is to get the game for yourself as the demo is free to play and it will give you a very good example of what the game is all about.
Oceanhorn Download: Android | iOS