My car is overheating

@muhammedtijani during low speeds there is not enough of a cooling effect hitting the radiator. Your Peugeot will rely entirely on the electric fans. Here is a quick check you can do. Open the hood while the car is idling and hot, to check if the fans are spinning. If not then you either have bad fan(s) or a bad fan relay.

Now once your car heat up to a certain temperature the fans are supposed to move to high speed to help it stay cool. You should hear a difference when those fan go high. The other things you definitely want to check are proper coolant levels. Do a pressure test on the radiator to check for leaks and checks the radiator cap for proper function as well. Also, there is always the possibility that your water pump is starting to fail and just can no longer circulate enough coolant to keep the engine temperature at a proper level.

Anytime you work on the coolant system of your car you want to be extremely careful that you do not open anything that is under pressure while hot i.e. radiator cap etc.

Since you did not tell us what year your car is here is the 1993 1999 Peugeot 306 repair manual I have. Hopefully it'll help you out.