The document discusses the past tenses in Spanish: the preterite and imperfect.
The preterite uses different endings for each subject and verb type (AR/ER/IR). It generally translates to the simple past tense in English. The imperfect uses more regular endings and generally translates to the past progressive, habitual past, or descriptive past in English. Both tenses have irregular forms for some common verbs like ser, ir, and ver.