For example: Fishing jetties require either a 'River 1' or 'River 2' type village, before they can be placed into that village type on the water.

A different village type can either be purchased by buying a new village or by converting your current village.

You would need the correct level of rank before you can buy an additional village, along with the correct amount of gold and a captain to purchase one.

Please see the wiki for more information: http://help.strongholdkingdoms.com/index.php/Village

And: http://help.strongholdkingdoms.com/index.php/Village_Table