To understand the difference between the imparfait (imperfect) and the conditionnel (conditional) and when to use them.
The imparfait is a past tense. The closest translation for it is the Imperfect or Past progressive or continuous.
Je jouais au tennis tous les mercredis. = I used to play tennis every Wednesday.
Je regardais la télévision lorsque quelqu'un a frappé à la porte. = I was watching TV when someone knocked on the door.
Il faisait beau et les oiseaux chantaient = It was sunny and the birds were singing.
Quand j'étais enfant, je rêvais de devenir chanteur = When I was a child, I used to dream of becoming a singer.
The conditional is a tense which describes an action that may happen if another action takes place.
Je sortirais s’il faisait beau = I would go out if the weather was nice.
Well, it is because the endings of the imperfect and conditional are exactly the same.
The sound varies. You will hear R for the conditional, because the stem used in the conditional is the same one as in the future tense.
Reminder: these verbs are highly irregular.