La cajera me explicó la comisión antes de que yo firmara.

The cashier explained the fee to me before I signed.

Breakdown of La cajera me explicó la comisión antes de que yo firmara.

• yo: I
• me: me
• .: period
• explicar: to explain
• antes de que: before
• firmar: to sign
• la comisión: the fee
• el cajero: the cashier

Questions & Answers about La cajera me explicó la comisión antes de que yo firmara.

What does la cajera mean, and why is it feminine?

La cajera means the (female) cashier. Spanish nouns have grammatical gender, and cajero/cajera changes form depending on the person’s gender. If the cashier were male, you’d say el cajero.

Why does it say la cajera (the cashier) instead of una cajera (a cashier)?

La is used when the speaker treats the cashier as a specific, identifiable person in context (e.g., the one at the counter). Una cajera would sound more like “some cashier,” introducing her as non-specific.

Why is me in me explicó? What role does it play?

Me is an indirect object pronoun meaning to me. The verb explicar commonly works like explain (something) to someone:

• me = to me
• la comisión = what was explained (direct object)

So La cajera me explicó la comisión = “The cashier explained the fee/commission to me.”

Could I also say La cajera explicó la comisión a mí?

Yes, but it usually sounds unnecessary or emphatic. Spanish normally uses the pronoun alone: me explicó. You add a mí mainly for contrast or emphasis (e.g., “to me, not to someone else”):

• Me explicó a mí, pero no se lo explicó a mi amigo.

Why is it explicó (preterite) and not explicaba (imperfect)?

Explicó (preterite) presents the explanation as a completed event: she explained it (once) before something else happened.
Explicaba would emphasize the explanation as ongoing/background (e.g., “she was explaining it when…”). With antes de que, preterite is very natural because you’re placing one completed event before another.

Why does antes de que require the subjunctive?

Antes de que introduces an event that is not presented as a fact at the time of the main action, but as something anticipated/expected. That uncertainty/“not yet realized” viewpoint triggers the subjunctive in Spanish:

• antes de que yo firmara = before I (would) sign / before I signed (from that earlier viewpoint)

Why is it firmara and not firmé or firmaba?

After antes de que, Spanish uses subjunctive, so firmé/firmaba (indicative) don’t fit.
Because the main verb is in the past (explicó), the subordinate verb typically goes in the imperfect subjunctive: firmara. It expresses an action that was still pending at that point in the past.

Is firmara the only option, or could it be firmase?

Both are correct: firmara and firmase are two forms of the imperfect subjunctive. In everyday modern Spanish, -ra forms (firmara) are more common.

Why is yo included in antes de que yo firmara? Can it be omitted?

Yes, it can usually be omitted: antes de que firmara.
Including yo adds clarity or emphasis, especially because the subject changes (cashier → I), or if the speaker wants to stress that I was the one signing.

Could this be said as antes de firmar instead of antes de que yo firmara?

Usually, antes de + infinitive is used when the subject is the same for both actions (e.g., Me lavé las manos antes de comer).
Here, the cashier explains, and I sign (different subjects), so antes de que + subjunctive is the standard structure. You could still see antes de firmar in some contexts if the subject is understood as me, but antes de que yo firmara is clearer and more explicit.

In Spain, does comisión here mean a sales commission?

In this type of sentence, especially with a cashier, la comisión very often means a fee/charge (e.g., a bank fee, card fee, or service charge), not a salesperson’s commission. Context (bank, store, card payment) usually makes that meaning clear.