The document discusses the imperfect progressive tense in Spanish. The imperfect progressive uses the imperfect form of the verb estar along with the -ing form of another verb to describe an action that was ongoing in the past. Some examples are provided, such as "Yo estaba trabajando para él los martes" (I was working for him on Tuesdays). The imperfect forms of estar that are used in the imperfect progressive are listed. The steps for forming the -ing form of verbs in Spanish are also outlined.