This is a typical Pasar Malam. Pasar means market and malam means night in malay.
In the olden times, vendors would sell their wares during the night by the roadside. But nowadays, everything is very organized, so we have this pasar malam under a huge tent, where all the different vendors would sell their goods during the day and night but the crowd would normally comes during the night where the weather is cooler. The different vendors sell all different kinds of stuff from food to clothes and household items and you can actually bargain with some of the stalls over the prices of items.
The pasar malam is not permanent and only for a period of days and then they moved to another heartland of Singapore and start all over again.