Hi, my CT Scan which was done to look for any masses on my ovaries & adrenal glands found a moderate sized, fat containing umbilical hernia. What does?

See a surgeon. You need to see a surgeon to see if this needs to be left alone or operated on. Generally, these are not left alone and are operated on in an elective manner.
No problem. If it found only fat, not an outpouching of intestine, you can ignore it. Sometimes having all this advanced imaging capabilities gives us data we don't need.This is one case where it did. If you have lived to adulthood with this hanging around doing nothing, it will continue.