What does development proceeds toward greater complexity self-regulation and symbolic and representational capacity mean

Development proceeds towards greater complexity-

A pervasive characteristic of development is that children's functioning becomes increasingly complex-in language, social interaction, physical movement, problem solving, and virtually every other domain.

Self regulation-

controlling one's behavior, emotions, and thoughts in the pursuit of long-term goals. More specifically, emotional self-regulation refers to the ability to manage disruptive emotions and impulses.

symbolic and representational capacity-

something visible that by association or convention represents something else that is invisible

i may have all this wrong i'm not sure what you're studying or what lesson you're in