I recently started playing Fortnite Zero Build Battle Royale with my kids because they were really excited about playing that game with their friends. No stranger to first person shooter games, though I haven't really played them since Counter-Strike and Battlefield 1942 (which were a few decades ago), I figured I could represent enough. Needless to say, there was a brief learning curve as I worked though the particulars of Fortnite and spent many hours getting my butt kicked by people who were a lot younger than me (though in my defense, they likely have a lot more time to practice than I do). I did get better, and while I do not consider myself close to being a top tier player, I enjoy the time I play with my kids, especially those few times we win a Victory Royale.
Having said all that, my son got this book from the library to help our Fortnite game. It is a decent enough game guide to give you an understanding of the basics, but some of the information is outdated since the game has had several seasons since it was published; different gear, rules and options are present. There are some good tidbits in here, but to really understand strategies and tips for surviving Fortnite Battle Royales, I would suggest watching the various YouTube and other Fortnite streamers (I learned a lot from Evolve Jake and would recommend him as a great option).