What's the plot of the first season?
The Wheel of Time takes place in what is technically the future, but due to the cyclical nature of time in the series, looks a lot like Earth's distant past. It's during a time known as the "Third Age," roughly more than three millennia past a cataclysmic event known as "The Breaking of the World," which put an end to a technologically advanced era known as "The Age of Legends." It's all very A Canticle for Leibowitz, but in this universe, magic (controlled through an ability known as "channeling") is real and society looks a whole lot like medieval Europe.
The first season of Amazon's adaptation is based off of the first book in the series, The Eye of the World, which follows Aes Sedai (an all-female magic organization) member Moiraine Damodred as she attempts to find the Dragon Reborn, a prophesized figure whose actions will eventually save or doom humanity. After arriving in the small town of Two Rivers looking for the Dragon Reborn, Moiraine is unable to ascertain which of a group of three young men -- Rand al'Thor, Matrim Cauthon, or Perrin Aybara -- are the Dragon Reborn. Accompanied by their friend Egwene al'Vere and wise-woman Nynaeve, the group sets off for the Aes Sedai city of Tar Valon, avoiding forces sent by the Dark One that are also in search of the Dragon Reborn.