Supergirl is one of the Story Pack characters in LEGO Dimensions 2: The Rise of Enoch, from the DC Comics franchise.
Kara Zor-El is Superman's teenage cousin who was sent to Earth at the same time as baby Kal-El to watch over him and help raise him. However, she was cryogenically frozen in space and didn't age. Years later, when Kal-El was now an adult and a superhero using the name Superman, Kara landed on Earth, still a teenager. She gained powers from living under "a yellow sun" and became her cousin's partner, Supergirl.
Like Nightwing, Batgirl, Huntress, Black Canary, Shazam!, Zatanna, Hawkman, and Hawkgirl, Supergirl occasionally works with the Justice League, which mainly includes Batman, Superman, Wonder Woman, Green Lantern, The Flash, Aquaman, Cyborg, and The Martian Manhunter.