It holds (supports) the sails.
You can also mount navigation systems on it.
a pole on a sailboat is a mast
Mast
The Mast
It is called the mast
masthead
Do you mean the mast?
Is called a mast
Mast
sailboat spars include the: mast boom sprit (if the boat has one)
The Mast
the snark
63'