There is no shortage of books to help us learn the Spanish grammar. The one I’m recommending, English Grammar for Students of Spanish, is indispensable if you already have some exposure to the Spanish language, perhaps, not in the formal sense, and you feel you need to delve into grammar to round out your learning, to fill in the gaps in your knowledge.
Perfect example of someone who found this book extremely useful is … me. After having been learning Spanish using Duolingo for years, I felt that the next step for me was to study its grammar. I already have in my possession numerous grammar books. So, why did I acquire yet another one? English Grammar for Students of Spanish, now in its 7th edition, is like the (missing) concise study guide to the grammar books that any Spanish learner may already have.
Each chapter in the book answers a basic grammar-related question, such as ‘What is the Subjunctive?’ and ‘What is the Imperative?’ This book is like the lightweight version of a college textbook that can comfortably sit on anyone’s study desk. You will find that many of your basic grammar questions are answered there.