Muscles and the brain
We take it for granted how easy it is to pick up and move something. Yet when your baby picks up and moves an object, they must be able to link the thoughts in their brains to the movements of their muscles.
To do this, they need to know what they're going to do before they move a toy or object. They will use their cognitive powers to think about the action they want to take, and then to do it your baby must combine their gross and fine motor movements.
Future skills
When your baby picks up and moves things, they are also developing new hand and finger movements. These movements will be necessary for a wide variety of learning and activities as they grow up, such as picking up a block and using it as a phone, picking up a spade and digging, and picking up a pen to draw.
Many of the things we do in life require both cognitive thinking and the movement of muscles. In time, this process will become automatic for your baby, but for now your baby uses a lot of energy to make such incredible decisions and movements.