A state property is a quantity that is independent of how the substance was prepared. Examples of state properties are altitude, pressure, volume, temperature and internal energy.
The state of a simple compressible system is completely specified by two independent, intensive properties. Two properties are independent if one property can be varied while the other one is held constant. Properties are intensive if they do not depend on size, e.g. the properties of temperature, pressure, entropy, density, specific volume.