Benign hydrocephalus?

Our seven month old daughter recently had a sono done to check for hydrocephalus due to quick head growth at out six month wellness vist. I just spoke to her doctor not too long ago and she said that everything looks fine but that they noticed some excess fluid around her brain, not in it and that it is considered benign. The whole call didn’t instill much confidence in me bc she did say she wasn’t sure if or just how often it should be monitored. Clearly I’m calling a neurologist on Monday for a second opinion but has anyone gone though this? I found one link on benign hydrocephalus and it didn’t provide any answers, just quick stats of frequency of it occurring. And a quick search just gives terrifying answers on hydrocephalus being water on or around the brain but she said the water around isn’t concerning bc it’s not causing tissue damage. So what in the hell makes this case benign.