Revisamos el pase antes de salir.

Because Spanish often leaves out subject pronouns when the verb already makes the subject clear.

Here, revisamos tells you the subject is we. So:

• Revisamos el pase antes de salir. = We check / checked the pass before leaving.
• Nosotros revisamos el pase antes de salir. is also possible, but nosotros is usually only added for emphasis, contrast, or clarity.

Revisamos can be either:

• present simple: we check / we review
• preterite: we checked / we reviewed

This is a very common overlap in Spanish for -ar verbs in the nosotros form.

So by itself, revisamos is ambiguous. Context tells you which meaning is intended.

Examples:

• Cada día revisamos el pase antes de salir. = Every day we check the pass before leaving. → present
• Ayer revisamos el pase antes de salir. = Yesterday we checked the pass before leaving. → preterite

Because the verb has to match the subject.

The infinitive is revisar = to check / to inspect / to review.

Its present-tense forms include:

• yo reviso = I check
• tú revisas = you check
• él/ella revisa = he/she checks
• nosotros revisamos = we check
• ellos revisan = they check

Since the implied subject is we, Spanish uses revisamos.

El pase usually means the pass, but the exact kind of pass depends on context.

It could be:

• an entry pass
• a boarding pass
• a security pass
• a backstage pass
• a permit or access pass

So pase is a general word for something that allows entry, movement, or access.

In other contexts, pase can have other meanings too, but in this sentence it most naturally means some kind of pass or ticket-like authorization.

Because el means the, so it refers to a specific pass that both speaker and listener already know about.

• el pase = the pass
• un pase = a pass

So the sentence suggests there is one particular pass being checked, not just any pass.

Because antes de is the normal structure in Spanish for before when it is followed by a verb in the infinitive.

The pattern is:

• antes de + infinitive

So:

• antes de salir = before leaving / before going out
• antes de comer = before eating
• antes de entrar = before entering

You need the de here.
So antes salir would be incorrect.

After antes de, Spanish normally uses the infinitive when speaking generally or when the subject is understood from the main clause.

So:

• Revisamos el pase antes de salir.

means:

• We check the pass before leaving.

The understood subject of salir is the same we from revisamos.

Spanish does this very often:

• Después de comer, descansamos. = After eating, we rest.
• Antes de entrar, llamaron. = Before entering, they called.

It can mean either, depending on context.

Salir is a broad verb that can mean:

• to leave
• to go out
• to go outside
• to depart

So antes de salir could be:

• before leaving
• before going out

The surrounding situation tells you which sounds best in English.

Yes. El pase is the direct object of revisamos.

Ask the question:

• What do we check?
• The pass.

That makes el pase the direct object.

Structure:

• Revisamos = verb
• el pase = direct object
• antes de salir = time-related phrase

Because the personal a is mainly used before specific people, and sometimes pets or personified beings, not ordinary things.

Since el pase is a thing, not a person, there is no a.

Compare:

• Vemos el pase. = We see the pass.
• Vemos a María. = We see María.

Yes. Spanish word order is more flexible than English.

You could also say:

• Antes de salir, revisamos el pase.

This means the same thing. The difference is mainly one of emphasis or style.

• Revisamos el pase antes de salir. focuses first on the action.
• Antes de salir, revisamos el pase. foregrounds the time sequence first.

Yes, depending on nuance.

These verbs are similar:

• revisar = to check / inspect / look over
• comprobar = to check / confirm
• verificar = to verify

Revisar often suggests looking something over carefully.
Comprobar often suggests confirming that something is correct.
Verificar can sound a bit more formal or technical.

So all may work, but revisamos el pase is a very natural choice.

Yes. Pase is masculine, which is why it uses el:

• el pase

That gender is grammatical, so it must be learned with the noun. Even though pase ends in -e, that ending does not automatically tell you the gender, so the article is important.