Ah sis, that's just the doctor's way of saying kung saan nakaposisyon ang placenta mo, sa case mo, it's at the back of your uterus (posterior) and it's completely covering the opening ng cervix (the os), which they're calling grade 1. At 5 months, this is actually common and most of the time it moves up on its own as your uterus grows, so don't worry too much! A few of us had the same finding and it resolved by the third trimester, pero definitely ask your OB about it in your next checkup para malaman mo kung kailangan follow-up ultrasound, they'll monitor kung mag-shift pa talaga or if it stays that way closer to delivery.