Arkandel has the right of it but... @tek.
It's easier to describe Sanderson's work by splitting it into different words.
First, the cosmre.
Brandon has built an entire universe that's interconnected and has several different 'worlds.' These worlds all have their own magic systems but as you read the books you come to realize that they are interconnected. It's not always clear HOW, but the more you read the more you find. What seems like a throw-away chapter/paragraph/section in one of the novels will take on ENTIRELY new meaning when you read a separate novel in the cosmere. He's had some drift over the years so if you read some of the earlier books, like Warbreaker, you have a little cognitive disconnect. However, as @Arkandel said, he is a METHODICAL planner. He does pause in some places and reevaluates his overall plan for the universe. Then in his future books he'll work to gather those stray ends back into the fold.
Many of his cosmre books are built in similar ways to the Wheel of Time books (fun fact, Sanderson was the one trusted to take Jordan's notes and finish that series after Jordan died.) There are usually 4-5 main characters who the point of view switches between, though the switching is NOT consistent. You can meet a character in the first chapter of a book, then not see them again until the final third. Often between his chapters he'll introduce minor characters that flesh out the worlds by showing the things the major characters simply wouldn't be able to know. His narration shifts from omniscient to limited perspective depending on the focus he's chosen. I found it REALLY difficult the first time I read A Way of Kings to keep everything straight, and even now, I can't say that I have it solid.
These books are ones I'm going to reread for the rest of my life and find new complexity to every single time.
YA Novels
If you want something less complex, these are the ones you want. They are called YA more because the age of the main characters than the content. These include the Reckoners (a finished trilogy), Starsight (2 books now, 3rd is in production), Alcatraz and the Evil Librarians (these I recommend even to elementary school kids, because they're full of a bunch of zanny humor that younger kids love. They miss the more adult themes, so if a parent can read them WITH their child? 10 points, both people will have fun), and The Rithmatist (a series in perpetual ???? WILL HE EVER WRITE MORE?! mode, it's sad.) With the exception of The Rithmatist you can put these books firmly into the science fiction category.
This is also where I suggest people start with Sanderson if they're not ready for the rest of the WORLD. They're fun, they're quick, and you won't regret the time you spend on them.
Novellas
Sanderson has dozens of smaller less than 100 page books. These are like candy for a starved reader. You can finish them easily within an hour but they tell a full and complete story. SOMEHOW he manages to build a fully fleshed world in these small novels. I've bought every single one I can get my hands on, and I still find ones I don't own and get annoyed that I don't own them already. These novellas stretch between genres, jumping between fantasy and science fiction depending on his whim. Some tie into the larger stories (see Cosmre and the YA novels) while others are totally stand alone.
Other
With all his amazing ideas I find it basically unfathomable that Sanderson can write in ANY worlds but his own, yet he has. There is the aforementioned finishing of the Wheel of Time books, some Video Game novels (seriously, they're like fan fiction but like, polished and published) and a Magic, the Gathering novel. I haven't read these (even the Wheel of Time - I never got past book for, but I was younger and stupider. Someday I'll do it.)
SO THAT IS BRANDON SANDERSON. If I haven't scared you off, I can give you a few starter titles.