Complex sentence: The second arch is utilized as a video screen and represents Mandragora, a plant creature whose vines have overtaken the abandoned theater with its plant-like "arms" that extend to nearly in length.
Split into simpler sentences: The second arch represents Mandragora, a plant creature whose vines have overtaken the abandoned theater; the arch is utilized as a video screen. It also has plant-like "arms" which extend to nearly in length.