[details=“English Translation”]Should he be given another chance, he would do his best.[/details] Si le dieran otra oportunidad or Si le diera or Si le diesen…what is the English equivalent?
Si le dieran, in this case, translates to If he / she / it were given, Here, the plural subjunctive form of the verb in the past is being used as to express the passive voice in Spanish. In essence, you saying ‘If they gave him …’ where the subject of the sentence is not known (I mean, who exactly are they?), making it a passive sentence.
Also, you should be aware that Spanish has two ways to conjugate verbs in the subjunctive mood in the past: either using endings -ara or -ase for ar verbs, or -iera or -iese for ir verbs. So, Si le dieran and Si le diesen are two alternative ways of saying the same thing. I suggest you choose to learn just one of them to begin with.
Why two things that mean the same thing? As I understand it, in Spain different regions have a preference for one over the other; but both are correct and understood. Occasionally, you’ll see both being used in text as a way of breaking up repetition or to give it some extra flourish.