From OpenStreetMap Wiki
|barrier = turnstile|
|A passage on foot through a fence|
|Used on these elements|
|Tools for this tag|
A(also called baffle gate) is used to allow one person at a time to pass. Use this for small turnstiles like the ones in supermarkets or some subways.
How to map
Also used for tagging some doors/gates/barriers where you validate your ticket, see Tag:railway=subway_entrance.
suggested by User:Chrisana13