Low coolant level will cause engine overheating, which may cause serious damage to the engine.
How to check the engine coolant level:
The coolant level should be between “LOW” and “FULL” marks in the coolant overflow tank as in the picture. If it’s lower, top it up. If there is no coolant in overflow tank or you have to top it up quite often, have your car inspected in the garage, possibly there is a coolant leak.
Never open the radiator or coolant overflow tank when the engine is hot!
When engine temperature is reduced (few minutes after the engine has been turned off) , simply add a coolant into the overflow tank to “FULL” mark.