The coolant or antifreeze that your vehicle uses depends on the year, make, model and engine of your vehicle. The purpose of coolant/antifreeze is to keep the engine cool under harsh operating conditions and also prevents damage in extreme cold conditions. It also provides anti corrosion protection due to the many different types of metals that your engine is made up of.
Water is not coolant and should not be used as such. It should ONLY be used in emergency situations until you can get more coolant/antifreeze in your car.