It may be called a Chicago bolt, or a sex-bolt because the other end will be a matching bolt-shape but with a blind hole for the threaded part to mate into.
If it were intended for a nut, then it would be called a shoulder bolt as per the other answer, but in this specific case its an axle for the scooter's wheel, so a nut is a mechanically bad choice.
Normally a scooter axle would have a female bolt and a male bolt like this:
Razr scooter axles
That your bolt has a threaded male section, combined with the shorter length suggests that it is from the latching part of the headset, and is intended to slide on a slot. If you can do away with the folding functionality, any bolt/nut combination that fits should be adequate when done up securely.
Hermaphrodite chicago bolts
Avoid a replacement bolt made from cheese-grade steel, try and get something a bit higher grade.
When you do replace it, look at using thread locker to secure the fastener on - scooters are high-vibration environments and things will back-out over time.