In detail, this is what is included:
Care Package: a ULC pack containing the Doomsday Prepper Pack, American Muscle Pack, Outlaw Pack, Chaos Pack and Explosive Pack [Available 8th of May 2018]
All Season Pass holders will get access to Far Cry 3 on the 29th of May 2018.
Hours of Darkness: Battle the Vietcong in Vietnam.
[Available 5th of June 2018]
Lost on Mars: You'll leave Earth behind to battle arachnids on the Martian surface.
[Available 17th of July 2018]
Dead Living Zombies: Pits you against zombie hordes in a variety of B-movie scenarios.
[Available 28th of August 2018]
More information on the contents of the Season Pass can be found on the Ubisoft Blog or the official Far Cry 5 website.
Stay tuned for more on Far Cry 5's post-release content plans, including more details on the three separate adventures and the map editor.