Symbolic function refers to the cognitive ability of young children to use symbols, such as words or images, to represent objects, events, or ideas that are not present. This ability is a hallmark of Piaget's preoperational stage of development, which occurs approximately between the ages of 2 and 7. Children begin to engage in imaginative play and can understand that one thing can represent another, allowing them to create mental images and scenarios that aid in learning and understanding their world.