Si el suelo está sucio, paso la mopa antes de acostarme.

Si means if, so the sentence expresses a condition: I only do this when that condition is true.

• Si el suelo está sucio... = If the floor is dirty...
• Cuando el suelo está sucio... = When the floor is dirty...

In many situations, both can be possible, but they are not exactly the same:

• si focuses on the condition
• cuando focuses more on the time/occasion

Here, si is natural because the speaker means: whenever the floor is dirty, I mop it before going to bed.

Spanish uses estar for a temporary or current state, and ser for more permanent characteristics or definitions.

So:

• El suelo está sucio = The floor is dirty right now / at that moment
• El suelo es sucio would sound like the floor is a dirty kind of floor or the floor is inherently dirty, which is not what is meant

Since dirtiness is a condition that can change, estar is the correct verb here.

Here, suelo means floor.

Be careful, because suelo can also mean ground/soil depending on context.

Examples:

• El suelo de la cocina = the kitchen floor
• El suelo del jardín = the ground/soil in the garden

In this sentence, because of paso la mopa, it clearly means floor.

In Spanish, it is very common to use the expression pasar la mopa, which literally looks like to pass the mop, but idiomatically means to mop / to run a mop over the floor.

So:

• Paso la mopa = I mop / I run the mop over the floor

This is a normal Spanish expression, especially in Spain.

Related expressions:

• pasar la aspiradora = to vacuum
• pasar un trapo = to wipe with a cloth

So although it may look strange word-for-word, it is very natural Spanish.

Because Spanish normally uses the definite article with many everyday objects when talking about a specific tool being used in a general, normal way.

So:

• pasar la mopa
• pasar la aspiradora
• lavar los platos
• cerrar la puerta

English often leaves the article out in these cases, but Spanish often includes it.

Here, la mopa means the mop, but in natural English we would usually just say I mop.

Because Spanish usually omits subject pronouns when the verb form already shows who the subject is.

• paso clearly means I do / I pass
• so yo paso is possible, but usually unnecessary

Spanish speakers add yo only when they want emphasis, contrast, or clarity.

For example:

• Si el suelo está sucio, paso la mopa... = neutral
• Si el suelo está sucio, yo paso la mopa, no mi compañero. = emphasis/contrast

The present tense here expresses a habitual action or a general routine.

It does not necessarily mean the speaker is doing it right now. It means something like:

• If the floor is dirty, I mop before going to bed
• Whenever the floor is dirty, I mop before bed

This is a very common use of the Spanish present tense, just like in English:

• If it rains, I stay home
• When I’m tired, I go to bed early

Because this is a real or possible condition in the present or as a general rule.

A common pattern in Spanish is:

• si + present, present
• Si tengo tiempo, voy.
• Si llueve, no salgo.

So:

• Si el suelo está sucio, paso la mopa...

This means the condition is realistic and ordinary.

Spanish does not use a future tense after si in this kind of sentence. So you would not say:

• Si el suelo estará sucio... ❌

It means before going to bed or more literally before lying down myself.

Breakdown:

• antes de = before
• acostar = to put to bed / to lay down
• acostarse = to go to bed
• acostarme = to go to bed myself / to put myself to bed

So antes de acostarme is:

• before going to bed
• literally: before putting myself to bed

After antes de, Spanish normally uses an infinitive when the subject is the same as in the main clause.

Because after antes de, Spanish uses the infinitive, not a conjugated verb, when the subject stays the same.

So:

• antes de acostarme = before going to bed
• not antes de me acuesto ❌

This is similar to English:

• before going to bed not
• before I go to bed in this exact structure

If you want a full clause, Spanish would need something else, for example:

• antes de que me acueste = before I go to bed

But in your sentence, the infinitive structure is the natural choice.

Because acostarse is a reflexive verb, and in Spanish reflexive pronouns are attached to the end of an infinitive.

So:

• acostarse = to go to bed
• acostarme = to go to bed myself
• acostarte = to go to bed yourself
• acostarse = to go to bed himself/herself/yourself

This is normal with infinitives:

• quiero acostarme
• antes de acostarme
• voy a acostarme

If the verb were conjugated, the pronoun would go before it:

• me acuesto

Not exactly.

• acostarse = to go to bed
• dormirse = to fall asleep

They are related, but not the same action.

Examples:

• Me acuesto a las once. = I go to bed at eleven.
• Me duermo a las doce. = I fall asleep at twelve.

In your sentence, antes de acostarme means before going to bed, not before falling asleep.

Yes, it is grammatically possible, but Si el suelo está sucio... is the more neutral and natural word order.

Spanish word order is flexible, but the version in your sentence sounds more standard for everyday speech:

• Si el suelo está sucio... = most natural/neutral
• Si está sucio el suelo... = possible, but can sound more marked or stylistic

A learner should usually prefer Si el suelo está sucio...

It is perfectly understandable everywhere, but it does feel especially natural in Spain, mainly because of mopa and the expression pasar la mopa.

In other Spanish-speaking regions, people may also say things like:

• trapear
• pasar el trapeador
• pasar el trapeador al piso
• mapear in some places

So the sentence is good Spanish in general, but the vocabulary choice fits Spain very well.

Sometimes in natural English that translation may sound fine, but it is not the most exact one.

More exact:

• antes de acostarme = before going to bed
• antes de dormirme = before falling asleep

In everyday English, people sometimes blur that difference, but in Spanish it is useful to keep them separate.

So for learning purposes, the best translation is before going to bed.

By default, it sounds like a habit, routine, or general rule.

• Si el suelo está sucio, paso la mopa antes de acostarme. = If the floor is dirty, I mop before going to bed.

This sounds like something the speaker usually does whenever that situation happens.

If you wanted a specific one-time situation, Spanish would normally give more context, for example:

• Si el suelo está sucio esta noche, pasaré la mopa antes de acostarme. = If the floor is dirty tonight, I’ll mop before going to bed.

So the original sentence most naturally expresses a repeated behavior.