Ashley mentioned a few of these resources that are worth checking out. I've listed the US Amazon links, but you can find these titles elsewhere as well.
The Player:
https://www.amazon.com/Player-Tim-Robbins/dp/B000YMJ7SU/
I watched this the first time in a film school marketing class. As Ashley mentioned, despite being 30 years old, it's still the most accurate portrayal of Hollywood life to date.
Adventures in the Screen Trade:
https://www.amazon.com/Adventures-Screen-Trade-Hollywood-Screenwriting/d...
This is the William Goldman book that Ashley quoted from. This one is 40 years old but still relevant when it talks about how Hollywood works. It's also very entertaining with stories about his successes and failures and one story of him playfully stalking Sylvester Stallone in a Beverly Hills swimming pool to verify his height.
Which Lie Did I Tell?:
https://www.amazon.com/Which-Lie-Did-Tell-Adventures-ebook/dp/B00GVZMYVG/
This is Goldman's follow-up memoir and every bi as entertaining as Adventures in the Screen Trade.
Not mentioned by Ashley:
Tales from the script:
https://www.amazon.com/Tales-Script-Shane-Black/dp/B00329PYH0/
A series of interviews with A-list screenwriters back in the 1990's. There is also a book by the same name with similar interviews.
Milius:
https://smile.amazon.com/Milius-John/dp/B077MVDD63/
I see this as a cautionary documentary about how not to act in Hollywood.
Overnight:
https://smile.amazon.com/Overnight-Troy-Duffy/dp/B07X44W77C/
Another cautionary documentary, this one about a guy who blew up his career on his first deal.
