There's a reason this game is rated so highly throughout the board game world - it's a fantastic game!
each round you chose which role you would like, which provides a bonus to the action which is done by everyone. Do you create a new plantation? Build a building? produce goods? sell goods? recruit more colonists? ship goods..? The options and routes to victory in this game are endless making no two games the same!
Although it says 3-5 players, there is an 'official' set of rules for 2 players which works very well as I recommend to check out. Although perhaps not the easiest game to get the hang of, definitely one you will want to own once you get into gaming (in particular "euro games"). It's a classic!