Electronic road pricing is a way for the government to control traffic and reduce congestion on the roads in Singapore. Basically, it means that cars have to pay money to drive on certain busy roads during certain times of the day.
This is done using special devices that are fitted in cars, called "in-vehicle units" or IU for short. When a car drives on a road that has electronic road pricing, the IU will send a signal to a gantry (a sort of metal frame) above the road to let the government know that the car is there.
Then, depending on the time of day and how busy the road is, the government will charge the driver a certain amount of money. The more congested the road is, the higher the price. The money is automatically taken out of the driver's cash card, which is a special card that can store money just like a debit card.
This might seem kind of annoying or unfair for drivers, but it actually helps to reduce traffic on the roads and make it easier for people to get around. And, since the pricing is based on how busy the road is, it's also a way for the government to encourage people to drive during less busy times or take public transportation instead. This helps to reduce air pollution and make Singapore a nicer place to live for everyone!