Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is a sequel to Superman (1978) starring Christopher Reeve as the caped crusader. In this one, Superman sacrifices his powers to have a romance with Lois Lane, but three evil super-criminals from the planet Krypton have been released and travel to Earth to take it over.
After landing on Earth the three aliens, Ursa, General Zod, and Non, are walking in the woods next to a lake. Ursa sees a snake and picks it up out of curiosity saying "Oh, a primitive sort of life form." The snake turns around slowly and bites her on the arm. She throws the snake to the ground in disgust and burns it to death with red rays that come out of her eyes. She's surprised at her new eyeball death-rays and declares "I have powers beyond reason here!" Zod tells her that they all have the powers.
Non then reaches into the fire and picks up the charred black snake. He grunts and tries to test out his own eyeball death-rays but they are too weak and he throws the snake away in disappointment.
The snake used here is a harmless gopher snake or pine snake, not a venomous snake, but in the movie universe all snakes are deadly, so we're probably supposed to think that it's a deadly snake. We hear rattling sound effects, so they probably want us to believe that it's a rattlesnake. Whatever it is, Ursa just says "Ow" and is completely unharmed. Unlike the barbecued snake.