There are 4 towers in that island. There is one beacon tower. The beacon tower shoots out 4 beams.
You go to one of the tower, climb up to the top and look out at the view. You will see the beacon tower.
Then you do the puzzle on that stand to time what your tower shoots out to the the beacon tower.
Once that is done, go down and go to another tower and time that one to the beacon tower.
You do this to all the 4 towers.
You know when you're synched when it is synched. I mean when the towers shoot the beams at the same time. You know what I mean.