First result on google say it’s valentine’s day gimmick from 2015:

https://lovelockdiaries.wordpress.com/2017/05/22/wishing-bells-in-singapore/

The tempation, just putting your hands against them and start running, the Sounds they could make…

Love locks I believe. A couple writes their names on the lock, attach it to a bridge or structure and then toss the key as a symbol that their love is forever.