You better be ready. There are a lot of Goblins with a few Hobgoblins backing them up. The biggest have yet to come though. Get through the first round. Use all the cover to thin through the ranks. As much as possible, keep your distance. While the Vex can teleport, the distance helps. This is just the beginning. Keep your health up and have a good distance between the Vex and you.
You will advance to the next part of this massive fight after you clear out all the Vex in the area. There are Vex in the middle of the area and more on the outskirts. The next part begins when the Heart of the Garden releases some energy into the first of 3 statues.