in out first play we have a doubt about the buying goods action. The rule say that you can buy one good ( one cube) on an island. Does that mean that if my ship is near two island i can take one good per island?
No, it just means that you can choose from which island you take a cube. Basically the same as for the other actions (eg. when drawing turtles you just draw on one island, you only bring one tourist to one island, you only build one hut etc.)