Phytolacca americana, the American pokeweed. The berries are poisonous

If you are in a warm place, this is highly invasive. I think every one of those seeds germinate, given a chance. And if it wandered into your garden, you need to dig it out. A piece of the root left behind by pulling it out will grow back.

yes I agree with the id. I think it is one of your native plants. pretty but can be invasive.
welcome to GoY too :o)