Hey mama! Congrats on your ultrasound! "Posterior high lying" basically means ang placenta mo ay nasa likod ng uterus at medyo mataas ang position, totally normal lang and nothing to worry about, maraming moms namin ganyan din! It's just the doc describing where your placenta is positioned, which they track throughout pregnancy para sure everything's developing well. If may ibang details na unclear or gusto mo talaga detailed explanation, best to ask your OB directly kasi sila ang makakaintindi best ng complete picture ng ultrasound mo, pero based sa what you shared, normal lang yan!