No definitive answer can be given. Sizes vary.
This varies by manufacturer, please be more specific.
You are describing the mast.
Stays support the mast on a sailing boat running from the mast forward and aft. Shrouds also support the mast and run from the mast to the sides of the boat.
The rearmost mast on a ship is called the "mizzen mast." In a traditional sailing vessel, the mizzen mast is typically located behind the main mast and is used to support the mizzen sail. This mast plays a crucial role in the vessel's overall rigging and sailing performance.
The mast.
IF you meant the 'mizzen mast' - in relation to sailing - it's the mast immediately aft (or behind) the main mast.
A mast.
On a sailing ship, possibly on the mast.
No, the mast is a vertical post that holds the sails on a sailing vessel.
On a sailing vessel having more than three mast, the mizzen mast is the third mast immediately aft of the main mast. It is a shorter mast than the foremast. It is often located over the stern of the boat or ship. Correction to the above: a "Yawl" or a "Ketch" has two masts -a mainmast and a mizzen, with the mizzen sometimes located right on the transom at the stern.
If a sailing ship has two masts, and the aft is shorter than the fore mast, then the aft mast is called a mizzen mast. And it is in english.
Barques, schooners, brigantines.