Besides narrating habitual or repeated actions, states and condition in the past, the imperfect is also used to talk about ongoing actions in the past. Notice that none of these contexts require specific reference to when the action began or ended. The imperfect never expresses a definite beginning or end. Remember this is the main characteristic to clearly distinguish between the preterit and the imperfect. Ongoing actions expressed with the imperfect in Spanish can be conveyed in English either with a) the simple past or b) the past continuous.
Laura worked at a travel agency.
Pablo enseñaba literatura española en la universidad.
Pablo taught Spanish literature at the university.
Agustín tocaba el saxo en una banda de jazz.
Agustín played the sax in a jazz band.
Simple Past
Laura trabajaba en una agencia de viajes.Laura worked at a travel agency.
Pablo enseñaba literatura española en la universidad.
Pablo taught Spanish literature at the university.
Agustín tocaba el saxo en una banda de jazz.
Agustín played the sax in a jazz band.