It's Basella rubra, a vine commonly known as Malabar spinach. It would have had small, white or pink flowers, and these have now become the green seeds you're seeing on the stem, which then turn black. It's not actually a true spinach, but the leaves are edible and can be used in salads. It's a perennial plant, but only in areas which are frost free with warm winters. More info below, though the image isn't great
Here's a better picture of a Malabar Spinach plant.