The document discusses the preterite tense in Spanish. It notes that the preterite tense is used to describe actions or states that were completed in the past. It then provides details on how to form the preterite tense for different types of regular and irregular verbs. This includes changes to stem vowels and endings for verbs like -car, -gar, -zar, -ir, and -er verbs. It also lists several common irregular preterite verb forms.