The map screen shows you the map of Ruli Island, places you have been to and dungeons you can challenge.
Dungeons and places are indicated by small pictures with a colored frame. Those frames can have three different colors:
Indicates a place you can "jump" to by selecting it and pressing the A-Button (you must have visited the place at least once to be able to go there via map screen).
Indicates a dungeon you can challenge. There are red squares above the name of the dungeon, indicating the difficulty level of it. 1 = very easy, 5 = very hard.
Map dungeons don't get you any experience, but they harbour nice items and you get a reward for clearing them.
Note: There are some dungeons and places on the map which won't be available anymore as you proceed in the game, so check the map screen as often as you can!
Indicates a place or dungeon you are unable to visit anymore.