The doors are part of a Hindu temple, Sri Mariamman Hindu Temple located in Chinatown . Gordon explained very well in his comments in my previous post.
At the door, devotees ask God to grant their requests by ringing the bells before entering. So that is the reason why the bells are there. They also purify themselves by washing their hands and feet, and sprinkling water on their heads. (Source: Uniquely Singapore)


I will post the pictures of the temple tomorrow. It will be very lovely and beautiful.