Learn French: Avec un autre destin, il aurait changé de parcours et étudié la médecine. - With another destiny, he would have changed paths and studied medicine.

The past conditional is formed just like the passé composé, but you put the helping verb (the auxiliary) into the conditional tense instead of the present tense. Here, we take avoir in the conditional (il aurait) and add the past participle of the main verb (changé). It translates to "he would have changed".

Why is there no helping verb before étudié?

In French, just like in English, when you connect two verbs in the same tense with et (and), you don't always have to repeat the helping verb. Il aurait changé... et étudié... means "he would have changed... and [would have] studied...". The auxiliary aurait applies to both past participles.

Why is it changé de parcours instead of changé le parcours?

When you talk about changing or switching something you use, follow, or possess, French uses the verb changer followed directly by de and the noun, with no article (no le, la, or un). For example, you also say changer de train (to change trains) or changer d'avis (to change one's mind).

We usually see the past conditional with a si (if) clause. Where is the condition here?