It's called the "Humanity Star". From their site:
"Visible from earth with the naked eye, the Humanity Star is a highly reflective satellite that blinks brightly across the night sky to create a shared experience for everyone on the planet.
Created by Rocket Lab founder and CEO Peter Beck, the Humanity Star is a geodesic sphere made from carbon fibre with 65 highly reflective panels. It spins rapidly, reflecting the sun’s rays back to Earth, creating a flashing light that can be seen against a backdrop of stars.
Orbiting the Earth every 90 minutes and visible from anywhere on the globe, the Humanity Star is designed to be a bright symbol and reminder to all on Earth about our fragile place in the universe."