Hello, welcome to the forum.
As I also comes from Ruby/Rails I had the same questions when I started 
But functional programming is not OOP, no object, no classes, and known design patterns doesn’t apply.
It’s just different.
But You might soon see that functional proramming brings You a lot of safety (no mutation) and a different mindset.
Now, when I write Ruby, I try to apply functional paradigm principles
Here are videos You might enjoy (as I did…)
There is also this recent topic, where some books are recommended…
