Vocabulary words are grouped alphabetically by topic. New word groupings are continually being added. In constructing language, vocabulary words are the bricks and grammar is the cement.  Learning vocabulary words must be accompanied with implementation into real-life communication.  Grammar by itself is like a pile of dry cement.  Vocabulary and grammar, together, unite to create language.  They are meant to work together. No doubt, a strong vocabulary will enrichen your Spanish speaking skills.