Paulo Abreu

I'm assuming that you don't have code experience, at all.

The Pragmatic Studio Ruby lessons are an excellent introduction to Ruby and Blocks. (1)

With "The Well-Grounded Rubyist, 3rd edition" (2), and "Metaprogramming Ruby 2" (3) you will get a better understanding of Ruby.

"Practical Object-Oriented Design (POODR)" by Sandi Metza is an excellent introduction to OOP (4)

The impostor handbook series will give you an introduction to many subjects that are necessary for a software developer (5).

"Data Structures And Algorithms In Ruby" by Hemant Jain touches on the main data structures. I don't know the book, and the first impression I got is that the author uses a C style, but at least the concepts have examples in Ruby.

"Design Patterns in Ruby 1st Edition" by Russ Olsen (6) and "Refactoring: Improving the Design of Existing Code (2nd Edition)" by Martin Fowler (7) are very well written books.

And, for testing, I think that "The Art of Unit Testing, Third Edition" by Roy Osherove is an amazing book! (8)

Do you need to read and study all this subjects before learning Rails? No way! It's work for a couple of years. I would start with the Pragmatic Studio videos and jump into the Rails Study. But if you want to learn faster and understand Rails, you need a long time study plan. Reserve one or two hours day for this.

(1) https://pragmaticstudio.com
(2) https://www.manning.com/books/the-well-grounded-rubyist-third-edition
(3) https://pragprog.com/titles/ppmetr2/metaprogramming-ruby-2/
(4) https://sandimetz.com/products
(5) https://bigmachine.io/products/the-imposters-handbook/
(6) https://www.informit.com/store/design-patterns-in-ruby-9780321490452
(7) https://www.informit.com/store/refactoring-improving-the-design-of-existing-code-9780134757599
(8) https://www.manning.com/books/the-art-of-unit-testing-third-edition