This document defines key grammar terms in Spanish including subjects, verbs, pronouns, adjectives, nouns, articles, prepositions, conjugation, infinitives, irregular verbs, and direct and indirect object pronouns. It explains that in Spanish, nouns must agree with adjectives and articles in gender and number, verbs are conjugated based on subject, and certain pronouns are used after prepositions or with certain verbs. It also notes some key differences in Spanish grammar compared to English such as different types of infinitives and irregular verb forms.