"Sodium" refers to the element sodium. "Dimonium" denotes a quaternary salt of dimethylammonium.
Phosphates are salts or esters of phosphoric acid, chlorides are salts of hydrogen chloride (hydrochloric acid).
Sodium Milkamidopropyl PG-Dimonium Chloride Phosphates is a substance used in cosmetic preparations where it acts as a foam booster (improves the foam quality by increasing volume, structure and/or durability), antistatic agent (reduces static charges by neutralizing the electrical charge on the surface of e.g. hair) and as a cleansing agent for skin and hair.