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 Brazilian road movie about Johann, a young German man who left Germany to avoid WWII and drives a truck around rural Brazil selling aspirin in 1942. He stops the truck in a small town, sets up a small screen and a movie projector, and shows films about how aspirin can cure your hangover and that sort of thing. People love the movies and line up afterwards to buy aspirin. His companion says with movies like these he could sell bibles to the devil. The companion's name is Ranulpho who was a hitchhiker Johann picked up on his way to Rio to look for work. At one stop, when Ranulpho was fetching some water from some farmers, Johann was sitting on a rock and suddenly felt something bite him on the ankle. He didn't see what bit him, and neither do we, but apparently it was a mildly-venomous snake because he was laid up in bed for two days and unwell for a while afterwards. The farmers told Ranulpho to cut and suck the bite so he did, in the classic cut and suck procedure which is no longer recommended.
Later, after Johann learns that Brazil has declared war on Germany and all Germans have to either return to Germany or go to a concentration camp in Brazil, Johann decides to get rid of his documents and hide from the authorities. He searches around a dry, cactus-filled scrubland for a place to hide them. He finds a large rock, and lifts it but there's a rattlesnake underneath. He picks up a large stick and almost whacks the snake, but he changes his mind, maybe because at heart he's a pacifist. In the end we see the snake crawling back into the rocks.
The snake is some sort of tropical rattlesnake, most likely Crotalus durissus, which is found in much of Brazil.