Once your baby is 4 to 5 months old, she’ll be fascinated as you pop up from behind your hands. By 6 to 8 months, she’ll be playing along, hiding and then giggling when she makes eye contact.
Your baby is learning about something called “object permanence”.
She enjoys the surprise element. You disappear and reappear, which is thrilling to her.
As baby grows, hold a blanket between the two of you she’ll have to plan to remove the blanket, reach for it, and pull it away.