Lol! I still don’t know what “arugula” is.
It is a very strong, almost bitter broad leafed Italian green.
My grandmother brought some seeds over from Sicily but her tribe called it "ladeek" and it was much stronger.
It was bitter but when she served it in a salad, it would be topped with hot bacon grease, onion and "dago red" wine. Still eat it today but not many folks like the strength when compared to the commercial "arugula".
Arugula is a green weed that I planted one year in my garden, and it comes back every year. It kind of tastes like wild dandelion leaves, which I also have plenty of.
I prefer the dandelion.