Si la hebilla del cinturón está rota, no puedo usarlo.

Si means if. It introduces a condition:

• Si la hebilla del cinturón está rota = If the belt buckle is broken
• no puedo usarlo = I can’t use it

So the whole sentence follows the common pattern If X happens/is true, then Y.

Because de + el normally contracts to del in Spanish.

• de el cinturón → del cinturón

So:

• la hebilla del cinturón = the buckle of the belt / the belt buckle

This contraction is required in standard Spanish, except when el is part of a proper name, such as de El Escorial.

Because Spanish nouns have grammatical gender:

• la hebilla is feminine
• el cinturón is masculine

This affects the articles and any adjectives that agree with the noun.

So in the sentence:

• la hebilla
• el cinturón

You just have to learn the gender along with the noun.

Spanish usually uses estar for a condition or state, especially one that results from something happening.

• está rota = is broken / is in a broken state

Here, the buckle is in the condition of being broken, so estar is natural.

Using ser here would sound wrong in normal Spanish, because ser is not usually used for this kind of temporary/resulting physical state.

Because rota agrees with la hebilla, which is feminine singular.

• hebilla → feminine singular
• adjective/past participle describing it → rota

Compare:

• La hebilla está rota = feminine singular
• El cinturón está roto = masculine singular

So the form changes to match the noun it describes.

It is historically the past participle of romper (to break), but in this sentence it functions like an adjective.

• romper → roto/rota
• está rota = is broken

This is very common in Spanish: a past participle is used with estar to describe a resulting state.

Lo refers to el cinturón, not la hebilla.

That is why it is lo and not la:

• el cinturón is masculine → lo
• la hebilla is feminine → la

So the meaning is:

• If the belt buckle is broken, I can’t use the belt

Even though the buckle is what is broken, the thing the speaker cannot use is the belt.

Yes. Both are correct.

• No puedo usarlo
• No lo puedo usar

When you have a conjugated verb plus an infinitive, the object pronoun can usually go:

1. attached to the infinitive
   
   • puedo usarlo
2. before the conjugated verb
   
   • lo puedo usar

Both mean the same thing. In this sentence, no puedo usarlo sounds very natural.

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

• puedo already means I can

So:

• no puedo usarlo = I can’t use it

You could say yo no puedo usarlo, but that would usually add emphasis, such as contrast:

• Yo no puedo usarlo, pero tú sí = I can’t use it, but you can

Spanish uses definite articles more often than English does.

In English, you might say:

• If the belt buckle is broken...

In Spanish, you normally say:

• Si la hebilla del cinturón está rota...

Spanish prefers the article with many nouns where English may be more flexible. In this sentence, all the articles sound completely natural and standard.

It is standard and helpful here because the si clause comes first.

• Si la hebilla del cinturón está rota, no puedo usarlo.

This comma separates the condition from the main clause. In careful writing, it is the normal choice.

Yes, but it means something slightly different.

• Si la hebilla del cinturón está rota = specifically if the belt buckle is broken
• Si el cinturón está roto = if the belt is broken

The original sentence is more precise. It focuses on the buckle as the damaged part.

The accent mark shows where the stress goes:

• cin-tu-RÓN

Without the written accent, Spanish stress rules would suggest a different pronunciation. So the accent is necessary to mark the correct stressed syllable.