Singapore use 230V, 50Hz
Typical plug is British 3-pin rectangular blade plug:
However, USA/Japanese 2-pin (type A) may be found from time to time.
Big and clumsy looking with a switch on the mains (outlets). However, the metal prongs are thick, sturdy, and not usually bendable like in some countries that don't use the UK compatible system.
The voltage is 220V so don't use American, Canadian, Japanese appliances unless they can withstand the higher voltage (usually they can't except a few travel things, like shavers and some battery rechargers)
Favorite thing: Singapore voltage is 220-240 volts AC, 50 cycles per second. When shopping for electrical appliances, do remember to check the voltage of the item against the acceptable voltage in your home country.