A Chemical Solution is any combination of two or more substances, one of which is usually dissolved into the other; in the case of gas solutions, the mixture must be in equilibrium, without settling or condensation. The substance being dissolved is called the Solute; the substance being dissolved into is called the Solvent. Solutions can be any combination of solids, liquids, and gases; however, a gaseous solvent can only dissolve another gas (air is composed of the solvent Nitrogen with the dissolved solute Oxygen and other gasses).
A typical example of a solution is salt water, or saline water; salt (NaCl, or Sodium Chloride) is dissolved in water (H2O) which binds the salt molecules and keeps it from precipitating. Since the salt dissolves completely, this is a solution. Also, the resulting solution is the same physical state as the solvent; in this case, liquid.
Most solutes are capable of a higher solubility when the solvent is at a higher temperature. The addition of solutes to solvents changes the chemical properties of each; salt water has a higher freezing temperature than fresh water, and ice forming in the ocean is generally turned fresh, with the salt removed in a process called brine rejection.