The absorbance of light gives solutions their color. The color and energy of light can be determined from its wavelength.
Electrons in atoms and molecules move around the nucleus in regions called orbitals or energy levels. An electron can move up to the next level if it is given the exact amount of energy required to be in the next level. Light can provide that energy.
When light is shone on a solution, some of the energy of light absorbed is affected by and transferred to the solvent. The light absorbance is spread out around a central maximum wavelength--lambda max.
There is usually more than one absorbance peak for a substance. Each local absorbance peak may be referred to as a local maximum.
Most solutions also do absorb, or solely absorb, ultraviolet (UV) light. The wavelengths most strongly absorbed typically occur in the UV. Often people refer to absorbance peaks of visible light as lambda max even when a stronger peak may occur in the UV region.