él supiese

knew

→ saber
sup to know + iese Imperfect subjunctive, third-person singular
verb · 3rd-person Rare #51,853
knew Used in the past subjunctive; often appears after expressions of wishing, doubt, or a condition.
SP: Ojalá supiese la respuesta.
EN: I wish I knew the answer.
Conjugation of saber
Subjunctive
supieransupiese

¡Ojalá supiese hablar inglés con la misma fluidez que tú!

I wish I could speak English as fluently as you!

Felix no quería que Sandra supiese donde vivía.

Felix didn't want Sandra to know where he lived.

Para que supiese cómo muere un hombre valiente.

So he would know how a brave man dies.

— El laberinto del fauno (2006)

Si supiese lo que significa para mí este asunto.

If you only knew what this matter means to me.

— Ladrón de bicicletas (1948)