I don't think that has been asked before. Here is my take on it.
They are not symbols, since she is fully cyberized those are access ports. Some for electrical connection, some for data, and perhaps even some for a screw driver to disassemble?
Here is a picture of a robot Geisha from episode 1. Head blown off, but a variation on the connectors remains visible.
In several episodes you see guards wearing 'dummy attack barriers' that are essentially disposable hardware firewalls against cyber attack. They were them the same way you'd wear a gorget.
My google-fu failed me and I could not find a picture of Aramaki wired up, but in one episode there is a scene where he wants to have a private discussion with a guy and so he physically links up with the guy using these jacks in the back of the head.
A lot of pictures show that folks are getting these as tattoos.
People tend to look at you a little strangely when they know you stuff voodoo dolls full of Ex-Lax.