It’s the wakaba mark. Wakaba means sprout, which is also used as a colloquialism for newbie. 🌱
It’s why new accounts in Final Fantasy XIV have sprouts next to their names.
I don’t think it’s fair to say that any symbols are self explanatory but these stand out and aren’t hard to recognise.
I’m from Europe, and I feel like our road signs are pretty intuitive, but they’re not, nothing is intuitive really. Things only feel intuitive because it aligns with your expectations.
As an example, to me a pedestrian crossing is a blue sign with a person walking over a striped road.

This to me is intuitive. It has the lined crossing indicating a crosswalk. It has a person walking over it. It’s blue, so it’s an informational marker.
When I visited the U.S. some years back, a particular sign kept cropping up everywhere, and I didn’t understand what it meant. It was yellow and said Ped Xing. After a few days I asked my friend who Ped Xing was, and why their name was signed everywhere. Why hadn’t I headed of them, if they seemingly did something to warrant their name being put all over the place? They had no idea what I was talking about until I pointed one out.
Mr/Ms Xing is actually Pedestrian Crossing. It sounds like a Chinese name to me, but somehow X is read as cross.

Our signs generally don’t have much text, and this just didn’t register as that for me. It didn’t help that many crossings weren’t striped, and not all crossings had Ped Xing watching over them. There was no pattern to infer meaning from.