WHAT DOES THIS MEAN?

I went to the doctor yesterday and I was told that my baby was in the "58th percentile." What exactly does that mean? My doctor told me that meant the baby would be 7/12 to 8 pounds when he was born. Anyone wish to elaborate?

00
    09/04/14
    he would be a good size for a baby....one big baby u will be having
    1
    About Sidney
    Current: Brunswick, Georgia
    Birth: March 14
    On Moms.com since: Jan 30, 2014