A spot can be anything. If they talk about hemorrhage, they are talking about a bit of bleeding inside the fetus' skull. U.S. Is not a good screen for that, though, as anything can show up like that. It could be a bit of heavy calcium deposit of the skull (insert obligatory joke about "thick-headed) or a temporary change in the brain itself. Remember that the fetal brain is doing a lot of growing around this time and is undergoing a lot of changes.
It could be serious, certainly, but it also could be what we call an "artifact," a insignificant thing affecting the quality of the u.S.
The main reason for such a bleed, if that indeed is what it is, would be what is called an aneurysm, a swelling of the blood vessels in the brain. That is genetical in nature, meaning that it runs in families. If you don't know anybody in your near family who have aneurisms, or who have had strokes from an actual bleed, it is much less likely that the us showed anything significant.
Now, that is about the limit of what I know about this and it is a long time since I have looked at us, so anybody else, feel free to jump in.