This tense is what would have happened.  He left his job.  I would   have left my job too.

Take the conditional of haber + past participle

En tu lugar,yo habría aceptado la oferta de empleo.  (Conditional Perfect,past participle)

In your place, I would have accepted the job offer.

Si tu te sacaste el gordo en la lotería, ¿qué habrías hecho?

If you won the grand prize in the lottery, what would you have done?

El habría comprado un nuevo coche.

He would have bought a new car.

Ella habría hecho un viaje alrededor del mundo.

She would have made a trip around the world.

Si me llamaste ayer, yo habría ido a la playa contigo.

If you called me yesterday, I would have gone to the beach with you.

Clauses with the "past" or perfect conditional

Used with pluperfect subjunctive and conditional perfect.

Si hubiera pasado por el banco, habría comprado cheques viajeros.

If you had passed by the bank I would have bought travelers checks.

Si ustedes hubieran sabido, no habrían invertido en acciones de compañías de petróleo.

If you all had known, you wouldn't have invested in oil company stocks.

Habríamos sabido programar, si hubiéramos estudiado informática. 

We would have known how to program, if we had studied computer science.