It’s a Lateen Mizzen.
The line from the top to the end of the yard is a peak halyard.
The line to the bottom end of the yard is the bowline.
Missing from this drawing are all of the lines attached to the sail. Primary would be the sheet, attached to the bottom corner, or clew, of the sail. It’s a double block line. It might run from a boom kin sticking off the stern, up to a block at the clew, back down to the end of the boomkin, through a block and over the stern rail to a pin or cleat.
When the ship tacks, either of two things happen. If it’s a long tack, the sail gets brailed up tight against the yard. The bowline gets detached. The peak halyard hauls the yard to as vertical a position as possible.
The bottom end of the yard gets worked around the back of the mast, the bowline gets reattached and the peak halyard gets loosened so that the yard can set on the leeward side of the mast, the sail unbrailed and set on the new tack.
Or on a short tack, the ship simply tacks and the sail bears against the mast in a “bad tack” until the next tack, where whatever side of the mast the yard is on is once again to leeward.
On a big ship like Victory that would be common. Otherwise it might take 30 or 40 crew to do the operation. It’s not so much a driving sail as a steering sail.
Hope that helps.