We were discussing the news we ... in the previous lessona)

We were discussing the news we heard in the previous lesson.

Мы обговаривали новинки, которые мы слышали в прошлом уроке.

The first part of the sentence is in Past Continuous. The second part of the sentence is in Past Indefinite.

Past Continuous is formed with the help of the second form of the auxiliary verb to be was / were (was is used for singular and were is used for plural).

Past Indefinite is formed with the help of the suffix ed for regular verbs. For irregular verbs we use the second form of irregular verbs.

Hear is an irregular verb.