to help them release the air trapped inside. as they grow they will learn to burp on their own. until then as parents please make sure you burp them during and after feed.
you need to rub their backs or pat lightly on their back to help them burp.
hold the baby in a position where baby’s head is resting on your shoulder and you support the baby’s bottoms with your arm. while in this position pat the baby’s back lightly ( or pressure which suits for your baby). sometimes baby might burp immediately or sometimes it may take time. keep on patting until the baby burps. this position is also beneficial 