"Co-wash" stands for "conditioner wash". This moisturizing co-wash from Curlygirlmovement is a great product to use between shampoos to keep the hair and scalp from becoming too dry or stripped of necessary oils and moisture.
CW says... A smaller amount of butters, oils, and some additional protein in this formulation will keep it from being too heavy or moisturizing. You can still use it on finer hair types.