“Before the sun sets on her sixteenth birthday, she shall prick her finger on the spindle of a spinning wheel...and die!”
The Spinning Wheel is an enchanted object which, when touched the spindle, will send its victim (in this case Aurora) into Eternal Sleep, originally death which was cast by Maleficent but was softened by Merryweather. The victim of the Eternal Sleep can only be revived by True Love's Kiss.
The spinning wheel plays a major role in the film because it is used by Maleficent to cause her curse on Aurora to be completed. Since Maleficent wasn't invited to the baby's christening, she casted an evil spell upon Aurora that, before the sun sets on her sixteenth birthday, she would prick her finger on the spindle of a spinning wheel and die. This briefly caused lots of grief and sorrow on the kingdom, but Merryweather softened the curse into a deep sleep. Still fearing for Aurora's life, King Stefan orders that all spinning wheels be burned. Sixteen years later, Maleficent hypnotizes Aurora by transforming herself into the spinning wheel (or conjuring it). Aurora pricks her finger and falls asleep. Maleficent then captures Prince Phillip so he can't break her spell, but the Three Good Fairies manage to rescue him. Moments later, he battles and kills Maleficent and kisses Aurora, which revives her.
A spinning wheel is an item belonging to Rumplestiltskin, who has had the ability to spin since he was a child and was abandoned by his father. Years later, Rumplestiltskin's son Baelfire was a child during the Ogre Wars. The wheel appeared in his small home where they lived together and again, later, in the main room of his grand estate house where he held Belle captive. He also teaches a young Cora to spin straw into gold to marry Prince Henry. He tells her to think of a moment where she was humiliated and use that to motivate her. When asked what moment he chooses, Rumplestiltskin tells of his humiliation of a King's Duke where he made him kiss his boot. Cora chooses the moment when a young Queen Eva trips her whilst delivering straw to the noble court and being forced to apologize. Cora names the technique "blood-lust" to which Rumplestiltskin approves. Rumplestiltskin is periodically depicted sitting at his wheel and spinning, lost in thought, claiming it helps him to forget.
Maleficent also used a spinning wheel with a weakened version of the sleeping curse with other ingredients to drug herself. She later used it to put Aurora under a sleeping curse.
His wheel is also featured in Storybrooke. One night, Belle finds Mr. Gold spinning his wheel and making potions. David's voluntary submission to a sleeping curse to reach Mary Margaret in the Netherworld is enacted by him pricking his finger on the spinning wheel's spindle, which Gold refers to as "the old-fashioned way", referring to Maleficent's sleeping curse.
Cora is also seen by Mary Margaret and Regina with the spinning wheel in a spirit form within an enclosed room after Mary Margaret, David, Emma Swan, Captain Hook, and her daughter Regina Mills attempt to make communication with her.
With Maleficent having come to care about Aurora, the curse itself provides the spinning wheel. As Maleficent and Diaval race to the castle with Phillip in tow, the curse reforms a crude and deformed spinning wheel, among the destroyed ones King Stefan had locked away in the dungeons. The curse or maybe even the spinning wheel seems to be calling out to Aurora, leading her through hidden passages in the servants' wings, and causing an itch under her finger, until she finally pricks it and draws blood on the needle.
The spinning wheel that was used by Maleficent to put Audrey's mother into an eternal sleep, appears as a museum exhibit at the Museum of Cultural History. After all those years, it still works as Mal used it to send the museum security guard to sleep. Unlike with Aurora's case, the guard woke after hearing an alarm go off in the museum, implying that the spinning wheel is a dud, or only works on Aurora.
In the original fairy tale, instead of turning herself into a spinning wheel, the Dark Fairy disguises herself as a kindly old lady who offers to teach the princess how to spin thread, which is the way she tricked her into pricking her finger on the spindle.
An unversed boss, the Wheel Master, is possibly modeled from the wheel.
But whether the wheel became an unversed or not is questionable.
In some tie-in storybooks based on the 1959 film and on the stained-glass portrait in the Sleeping Beauty Castle at Disneyland Paris, Maleficent appears next to Aurora when she urged the princess to touch the spindle on the spinning wheel, despite the fact that she herself is the spinning wheel in the actual film.
In the movie, when Maleficent shows Flora, Fauna, and Merryweather Aurora lying on the ground after she pricked her finger, it looks like that her neck was broken.
The spinning wheel is never mentioned or seen ever again, since it was Maleficent, who was the spinning wheel all along.