I'll give you a non-plot spoiling primer of sorts for the first novel:
Setting
It's about 20,000 years in the future at the start of the story. Humanity has branched out into the galaxy and has evolved into a kind of feudal system with large nation states (planets) vying for power in one form or another. A brutal war was fought against machines designed to serve humanity, called the Butlerian Jihad, which has led to thinking machines being forbidden.
The Great Houses
The story revolves around a group of planets that are in a power struggle within the Landsraad (the feudal system). House Carino runs the show at this point, with the Padishah emperor being the seat of power. House Harkonnen is a very militant industrial power located on the planet Geidi Prime. The Baron Vladimir Harkonnen leads this house and is super manipulative and a smart kind of meglomaniac. House Atreides on the ocean planet Caladan is lead by Duke Leto, and are much more reserved in their use of power than the Harkonnen, but they're not a bunch of hippies. Harkonnens are like Barnes, Atreides like Elias - both very capable but different mindsets.
Arakis (aka Dune)
The oil of this future is a substance called Melange, but more commonly referred to as "Spice." It is the most valuable commodity and "he who controls the spice, controls the universe." It's a kind of drug that can extend life and in heavy doses give people super-human capabilities. But there are two big problems: it's deadly addictive, and only exists on the desert planet Arakis. So control of this planet is vital for humanity and naturally every great house (and others) wants a piece of it. Arakis is deadly and very inhospitable, with giant sand worms burrowing underneath attracted to vibrations in the soil. Spice harvesting operations, like oil rigs, is big business but it's exceptionally dangerous when that activity attracts sand worms.
The Spacing Guild
Among the great houses is a kind of freelancer group called the Space Guild which has a monopoly on interstellar travel. Guild Navigators consume huge amounts of spice regularly, which gives them the super-human capability to compute and plot spacetime folds (like warp speed travel). Their consumption of spice completely transforms them into these fish-like creatures that have to live in a chamber filled with spice vapor. Even though the Emperor runs the show, the Spacing Guild is extremely powerful and influential because all the great houses rely on their capabilities. You want to invade a planet? You hire the Spacing Guild to send you a Highliner (giant cylindrical space ship carriers) that you load your ships in and they take you instantaneously to your destination.
The Sisterhood of the Bene Gesserit
These women are another powerful group outside of the Great Houses and can essentially be thought of as space witches. They're a kind of religious order that aims to manipulate and control things from the shadows, guiding humanity in a direction that they prefer. They use spice to hone super-human like powers of the body and mind. They can read the smallest subtly in someone's demeanor to predict what they are thinking or what they are going to do (great for detecting deception). They can control every fiber in their biological processes, allowing them to do all kind of super-human physical things, and have a fighting style that uses all of those capabilities called The Weirding Way. Basically, everyone is scared of the Bene Gesserit to some degree. In the new trailer, the Reverend Mother is the scary lady with the box.
Mentats
Because thinking machines are forbidden at this point, there are humans that have been conditioned to become essentially super-computers by consuming spice and an offshoot called Sapho Juice. Every leader of a great house has a royal Mentant who advises them, along with computing needs.
The Fremen
The only humans permanently living on Arakis and supremely evolved to survive in the harsh environment. They have developed special gear called stillsuits that help them survive by processing all of their moisture into a closed-circuit that helps regulate their bodies. That's why you see folks in the trailer with those weird black outfits with hoses into the nose. The Fremen are religious zealots of sorts, patiently waiting for the arrival of their messiah in the form of the Quizat Haderach. Because they basically live surrounded in spice, they're all spice addicts to some degree, turning their eyes a deep blue within blue.
The story begins...
So the story centers around Duke Leto's son Paul, a teenager raised on Caladan who's been trained up by the House Atreides master swordsman Gurney Halleck (James Brolin in the new film) and their greatest warrior Duncan Idaho (Jason Momoa in the new film), but also trained by his mother Jessica, who is a member of the Bene Gesserit. So he's gotten an extremely rare skillset as a child: capable fighter with near mentat cognitive skill. He's 15 years old and big things are happening in the Landsraad. The Emperor wants House Atreides to take over spice harvesting from the Harkonnens (their bitter rivals) so Duke Leto is moving his center of power to Arakis, while Paul senses something awakening within him.