Sorry. Spelling it wrong. It's Aucuba. Or more specifically it's Aucuba Japonica.
You should definitely remove the leaf with the black spot. It's not going to get better but will just not ever be pretty again. One leaf here and there isn't bad. It's when the whole thing turns black then you know you have an ex-plant.
I think the main problem is too much water. This can cause root rot. And on and on. There are treatments for it but I'd start with cutting back on water. Probably would be good to remove it from the soil it's in. Is your plant in the ground or in a pot?
