It's a collection of programming exercises I used when I taught introduction to programming. They start out incredibly trivial, ("prompt for a name, print "hello [name]" back to the screen. But the trivial part is, in my opinion, the fun part when you work with a new language.
That program is a two line program in Ruby. But it might be much more complicated if you implemented that as your first GUI app in Swift for iOS.
I wrote the book to teach beginners, but I and others use those exercises to learn new languages. The book has no answers, just the problem statements.