It just means that out of 100 babies at the exact same gestation 32 would be smaller and the rest would be bigger. Exactly the same as adults, some babies are just bigger than others. Doctors are only concerned if it is under 5th or over 95th generally. Everything else is perfectly normal/healthy
They just like to see that your baby is following that curve as they grow 🤷🏻♀️
A baby can be a healthy baby in any percentile.
If the doctors aren't worried after a scan then I wouldn't be too concerned🫶🏼