The phrase "kids growing up" refers to children maturing and developing physically, emotionally, mentally, and socially as they move from childhood into adulthood. It is a natural process that involves changes in behavior, cognitive abilities, and social interactions. As kids grow up, they learn new skills, gain more independence, develop their own beliefs and values, and form relationships with others. The phrase can also be used to describe the various stages of childhood development, such as toddlerhood, early childhood, middle childhood, and adolescence.