Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is mostly an adventure at sea movie with a romantic side story and dialogue out of a hard-boiled pulp fiction paperback. Despite the title, there is very little serpent action once they finally get to the island. This is an example of the pitfalls of watching a movie because of its title, but it's almost fun to be reminded that people used to make movies as terrible as this one. Mystery Science Theater has lampooned several films made by the director of this movie, but this one is apparently not good/bad enough even for them.
The great grandfather of Ricky, a secretary from Scranton, hid a million dollars in gold treasure 150 years ago on an island near Haiti. She goes to San Pedro where she hires a large sailboat to take her to Haiti to search for the treasure. (Why she doesn't just fly or sail out of Florida is never explained.) She hires a guide named Pete, a San Pedro harbor bum, played by Sonny Tufts, who knows the area where the treasure might be located. It takes about two thirds of the movie to get to the Carribean island (which nobody ever calls Serpent Island in the movie) and when they get there they spend at least 10 minutes showing us a bunch of chicken-sacrificing voodoo dancers who are protecting the island from treasure hunters.
That leaves only a few minutes for the snake scene at the very end, but it's a classic of absurd action. When Ricky finally gets to a statue made of gold she sees a large snake which we're supposed to believe is guarding the treasure. She screams as the snake wraps itself around her, or more accurately, she wraps a disinterested sluggish snake around herself to make it appear like it is attacking her. She wrestles with it for a while, sitting down, standing up, lying on the ground, as the snake goes to sleep, until finally Pete shows up with a machete and saves her. Somehow. He must not have hacked it up with the machete and killed the snake because it comes back to get rid of a greedy bad guy in the end.
It's a live snake that is being wrestled, but it doesn't seem to be putting up much of a fight. You can see somebody poke it with a stick in one shot and you can see that its mouth is tied up with what look like brown leather straps. It appears to be a python, but I'm not sure what species.
Don't watch the movie, you can just watch the absurd battle with the giant snake on Youtube.