Learn Spanish (Spain): Mañana voy al casino, aunque no apueste nada. - Tomorrow I am going to the casino, even if I don't bet anything.

This is the main point of this lesson! When aunque is followed by the subjunctive, it means "even if" and describes a hypothetical, future, or unverified situation. Because tomorrow hasn't happened yet, the betting is just a possibility. If the speaker used the indicative (aunque no apuesto nada), it would mean "even though I am not betting anything," stating it as a current, absolute fact.

What is the infinitive of apueste, and why does it have an "ue" in the middle?

The verb is apostar (to bet). It is an "o-to-ue" stem-changing verb. Just like in the present indicative (yo apuesto), this stem change carries over to the present subjunctive forms for I, you, he/she, and they.

The translation says "don't bet anything", so why does the Spanish literally say "not bet nothing" (no apueste nada)?

Spanish frequently uses double negatives. When a negative word like nada (nothing/anything) comes after the verb, you are required to put a no before the verb. You cannot just say apueste nada.

Why does the sentence use the present tense voy for tomorrow instead of the future tense (iré)?

Just like in English, Spanish often uses the present tense to talk about the future when referring to fixed plans. Saying Mañana voy (Tomorrow I am going) sounds very natural and planned, whereas Mañana iré (Tomorrow I will go) can sometimes sound a bit more distant.