I never felt the need to know the name or what this spiky thing stands for. However, I just educated myself: an iron monument, modern art authored by Portuguese artist Jorge Vieira, called "Homem-Sol", in English it would be "The Sun Man", 20 meters tall, near the Vasco da Gama Center.
Apud Google: "Monumental sculpture inspired by the Sun, of vaguely anthropomorphic structure, along which ascends angular forms of rods and half-moons, evoking a human figure. It has about 20 meters, 15 tons and iron oxide as the final colour."
There