Learn Spanish (Latin America): Ojalá yo pudiera conceder deseos.

Ojalá usually triggers the subjunctive. If you use the present subjunctive (ojalá yo pueda), it means 'I hope I can' and suggests a real possibility. But when you use the imperfect subjunctive like pudiera, it changes the meaning to a hypothetical 'I wish I could.' It shows that granting wishes is impossible right now.

How do we get the form pudiera from the verb poder?

The imperfect subjunctive is always built from the 'they' form (third-person plural) of the preterite (simple past). For poder, that past tense form is highly irregular: pudieron. To make the imperfect subjunctive, you drop the -ron at the end (leaving the stem pudie-) and add the new endings (-ra, -ras, -ra, etc.). For yo, it becomes pudiera.

Why does pudiera translate to 'could' here instead of 'can'?

In English, 'could' is the past tense of 'can', but we also use it for hypothetical present situations, like 'I wish I could'. Spanish does a similar thing, but it uses the imperfect subjunctive of poder (pudiera) to show that the ability is imaginary or contrary to reality.

Since this sentence uses the subjunctive, why is conceder left in the infinitive?