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 Disney action-adventure-comedy loosely inspired by the Jungle Cruise ride at Disneyland that stars Dwayne Johnson as Frank Wolff, the river boat guide, and Emily Blunt as Lily Houghton, a woman who dares to wear trousers in 1916 when it was unheard of. Lily travels to the Amazon region of South America with her brother to find information about her father. They hire Frank to take them upriver on his boat. There are many jungle animals in the movie, including a pet jaguar, and lots of other action and comedy, but I'm only going to discuss the parts with snakes. One of the two main villains in the movie is an ancient Spanish explorer who was cursed and is now completely made out of snakes.
Most movies with the word "jungle" in the title have snakes in them, often on trees in the background, and we see plenty of those in this movie, but it is unusually filled with snakes.
The cursed ancient Spaniard who is made of snakes that I mentioned is named Aguirre (Edgar Ramirez). At the very beginning we see Aguirre and his men 400 years ago walking through the jungle (wearing full armor) when a coral snake jumps from a tree and bites him on the neck. He grabs his sword and decapitates the snake, but the damage is done. He is found by the Guardians of the Tree who take him to their village and nurse him back to life with a potion made from a magic healing tree. After he recuperates he attacks them and tries to steal the healing secrets, but he and his men are cursed and imprisoned. They are petrified and trapped in tree roots for hundreds of years until kaiser Wilhelm's son Prince Joachim (Jesse Plemons) arrives up the river in a German submarine and frees them to enlist their help in finding the magic healing tree. He wants to use its secrets to help him take over the world. This is when we first see that Aguirre is made of snakes.
Later we see that Aguirre's entire head and body are made out of snakes that can strike out to kill people. He can also shoot them at people. The snakes can also all leave at the same time, making Aguirre disappear, then travel somewhere where they can re-assemble themselves back into Aguirre. In one scene we see them crawl in groups up a tree then drop down onto a boat where they re-assemble again into Aguirre so he can fight Frank. In another scene we see Aguirre throw a large gold knife at Lily that misses her head then turns into a snake that attacks her before she throws it to the ground where Frank crushes it.
All of the snakes we see in the movie are computer-generated images, but most people won't notice since many of them are fairly realistic. There's no way they could have filmed the snake man with real snakes, so I'll forgive them. Fortunately, for once, the artists apparently researched the snakes of the Amazon because some of the snakes look similar to species that are found there. We see what are supposed to be coral snakes, green tree boas, rainbow boas, and boa constrictors and probably more that I don't recognize. Typical of most CGI films, the screen is so dark that it's hard to see the snakes, so there are also lots of snakes that are unnaturally brightly-colored so they stand out.