A liquid form of any substance is an intermediate form between the solid form and the gaseous form.
Decreasing the temperature of liquid water according to the phase diagram of would freeze it and we would have a phase change from liquid to solid (ice) at the freezing point of water.
Similarly, heating water to its boiling point would evaporate water and we would have a phase change from liquid to gas (water vapor).
Therefore, liquid water exists between its freezing and boiling point.