It is a handlebar lock that can be used to prevent the bicycle from tipping over when parked.

Usage Instructions:
Turn the ring in the “lock” direction, which is counterclockwise, to secure the handlebars.
Turn the ring in the “unlock” direction, which is clockwise, to release the handlebar lock.

Please Note:
Before riding, make sure to unlock the handlebars and ensure they rotate smoothly.
Do not ride with the handlebars fixed in place (with the ring in the “lock” position). This is dangerous and prevents normal handlebar operation.
Do not operate the handlebar lock while riding.