Revisamos el juego de llaves y el bombín.

Because revisamos is the nosotros form of the verb revisar, meaning we check / we inspect / we reviewed, depending on context.

For -ar verbs, the nosotros ending is -amos:

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

So revisamos tells you the subject is we, even though nosotros is not written.

It can mean either one.

In Spanish, revisamos can be:

• present tense: we check / we are checking
• preterite: we checked

The form is identical in both tenses for nosotros with -ar verbs.

So the exact time depends on context:

• Ahora revisamos el juego de llaves. = Now we’re checking the set of keys.
• Ayer revisamos el juego de llaves. = Yesterday we checked the set of keys.

Because Spanish often leaves out subject pronouns when the verb already shows who is doing the action.

In revisamos, the ending -amos already tells you the subject is we. So nosotros is unnecessary unless the speaker wants emphasis or contrast.

Compare:

• Revisamos el juego de llaves. = We check / checked the set of keys.
• Nosotros revisamos el juego de llaves. = We check / checked the set of keys.
  This sounds more emphatic, as if contrasting with someone else.

Juego de llaves is a fixed expression that usually means a set of keys or a key set.

Literally:

• juego = set / collection
• de = of
• llaves = keys

So Spanish uses juego de llaves where English often says set of keys.

This structure is very common in Spanish:

• un vaso de agua = a glass of water
• una caja de herramientas = a toolbox / a box of tools
• un juego de llaves = a set of keys

Because the sentence is talking about one set, and that set contains multiple keys.

So:

• el juego = the set
• de llaves = of keys

This is the same pattern as in English:

• the set = singular
• of keys = plural

If there were several sets, it would be:

• los juegos de llaves = the sets of keys

Spanish normally uses the article with each noun in a list when each item is being identified separately.

So:

• el juego de llaves y el bombín

is more natural than leaving out the second article.

In English, we often say the keys and lock cylinder or the set of keys and the cylinder, but Spanish commonly repeats the article:

• el libro y la revista
• la puerta y la ventana
• el juego de llaves y el bombín

It helps make the structure clear and sounds more natural.

In Spain, bombín can have different meanings depending on context. The two most common are:

• bowler hat
• lock cylinder / cylinder lock

In the sentence Revisamos el juego de llaves y el bombín, the context strongly suggests the locksmith/hardware meaning: the lock cylinder.

That is a good example of why vocabulary often depends on context. If you saw bombín by itself, you could not always know which meaning was intended.

Yes, in the lock sense, bombín is especially common in Spain.

In other Spanish-speaking countries, people may use different terms depending on the region, such as:

• cilindro
• cilindro de la cerradura

So if you are learning Spanish from Spain, bombín is a useful word to know.

Because bombín is a masculine noun.

In Spanish, noun gender is grammatical, so you have to learn the article with the noun:

• el bombín
• el juego
• la llave

Even though llave is feminine (la llave), bombín is masculine (el bombín).

Because after a noun like juego, Spanish often uses de + noun in a general classifying sense, without the definite article.

So:

• un juego de llaves = a set of keys
• una caja de herramientas = a toolbox / a box of tools
• un vaso de agua = a glass of water

Using de las llaves would sound more specific, as if referring to some previously identified keys. In many ordinary cases, de llaves is the natural expression.

In standard Spanish from Spain, llaves is usually pronounced roughly like YA-bes, because ll is commonly pronounced like y.

A simple approximation is:

• llaves → YA-bes

Also:

• v and b sound very similar in Spanish
• the e in -ves is a clear vowel, not like the English ee

Depending on the speaker and region, pronunciation can vary a little, but YA-bes is a good guide for most learners.

Yes, it could, but it would not mean exactly the same thing.

• las llaves = the keys
• el juego de llaves = the set of keys

So el juego de llaves emphasizes the whole set or bundle, not just some keys in general.

That difference can matter in practical contexts like security, maintenance, or locksmith work, where a set of keys is treated as one item.