At some point during this month, most babies are able to keep their head upright while being held in a vertical position. They are also learning to control movements of their arms, hands, and legs, which allows them to perform more complex activities.
Early actions might include exploring objects and being able to differentiate their shape, position, distance, and other specific attributes. As a result, babies at this age often want to grab everything with their hands and then take it to their mouth to continue the process of exploration.
Social skills also improve and babies will be interested in engaging with everyone, including their own reflections in the mirror.