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
Do you mean the mast?
Is called a mast
masthead
Mast
sailboat spars include the: mast boom sprit (if the boat has one)
63'
the snark
The Mast