Si esta silla está rota, me siento en la otra.

Si means if and introduces a condition.

In this sentence, Si esta silla está rota, me siento en la otra, the speaker is talking about a real, possible condition: if this chair turns out to be broken, they will sit in the other one.

This is a very common pattern in Spanish:

• si + present
• present / future / command in the main clause

Here, both verbs are in the present, but the meaning in English is often future:

• If this chair is broken, I’ll sit on the other one.

Spanish usually uses estar for a state or condition, and ser for identity or essential characteristics.

A chair being broken is seen as a condition it is in, so Spanish says:

• está rota = is broken

Using es rota would sound wrong here.

A useful way to remember it:

• ser = what something is
• estar = how something is / what state it’s in

They are completely different words:

• esta = this
• está = is (from estar)

So:

• esta silla = this chair
• está rota = is broken

The written accent is very important here:

• esta → no accent → demonstrative
• está → accent on á → verb

Because rota is an adjective and it must agree with silla, which is a feminine singular noun.

• la silla → feminine singular
• therefore rota → feminine singular

Compare:

• El libro está roto = The book is broken
• La silla está rota = The chair is broken

Because the verb here is sentarse, which means to sit down / to sit oneself and is reflexive.

So in the yo form:

• me siento = I sit down / I sit

Without me, siento usually comes from sentir, meaning:

• I feel
• I regret
• or sometimes I hear/sense

So:

• me siento en la otra = I sit on the other one
• siento by itself would mean something completely different

Because siento can come from two different verbs:

1. sentarse → me siento = I sit down
2. sentir → siento = I feel

So context matters a lot.

Examples:

• Me siento en la silla. = I sit on the chair.
• Siento frío. = I feel cold.

In your sentence, the reflexive pronoun me and the phrase en la otra make it clear that it comes from sentarse.

In Spanish, when talking about sitting on a chair, sofa, bench, etc., Spanish commonly uses en where English often uses on.

So:

• sentarse en una silla = to sit on a chair

This is normal Spanish usage, even though the English preposition is different.

More examples:

• Me siento en el sofá. = I sit on the sofa.
• Se sentó en la cama. = He/She sat on the bed.

Because Spanish can leave out the noun when it is already obvious from context.

• la otra = the other one
• understood noun: silla

So:

• me siento en la otra literally = I sit on the other [one]
• meaning: I sit on the other chair

You could also say:

• me siento en la otra silla

Both are correct. Leaving out silla sounds natural because it is already understood.

Because la otra here means the other one, not just another.

Compare:

• otra silla = another chair / other chair
• la otra = the other one

In this sentence, there are effectively two chairs in the situation:

• esta silla = this chair
• la otra = the other one

So the article la helps specify that it is the other chair.

Spanish often uses the present tense to talk about a future result when the condition is real and immediate.

So:

• Si esta silla está rota, me siento en la otra.

can naturally mean:

• If this chair is broken, I’ll sit on the other one.

Spanish does this very often. It can sound more direct or immediate than using the future.

You could also say:

• Si esta silla está rota, me sentaré en la otra.

That is also correct, and it makes the future idea more explicit.

Yes, absolutely.

Both are correct:

• Si esta silla está rota, me siento en la otra.
• Si esta silla está rota, me sentaré en la otra.

The difference is mostly one of style and nuance:

• me siento sounds more immediate, like a natural reaction
• me sentaré sounds more clearly future

Both would be understood perfectly.

Because in Spanish, after si for real conditions, you normally do not use the future tense.

So Spanish says:

• Si esta silla está rota...

not:

• Si esta silla estará rota... ❌

This is an important rule.

A very common pattern is:

• Si + present, present/future/command

Examples:

• Si llueve, no salgo. = If it rains, I’m not going out.
• Si llueve, no saldré. = If it rains, I won’t go out.
• Si llueve, quédate en casa. = If it rains, stay home.

Because silla is grammatically feminine in Spanish. That is simply part of the noun’s gender.

So it takes:

• esta silla
• la silla
• rota

You have to match all the related words to that feminine noun:

• demonstrative: esta
• article: la
• adjective: rota

This is grammatical gender, not biological gender.

Yes, depending on what you want to point to.

• esta silla = this chair (near me / close in context)
• esa silla = that chair (near you / not as close)
• aquella silla = that chair over there (farther away)

So the sentence changes slightly depending on distance or context:

• Si esa silla está rota, me siento en la otra.
• Si aquella silla está rota, me siento en la otra.

In your original sentence, esta means the speaker is referring to this chair.

Here it functions as an adjective.

It comes from the past participle of romper (roto/rota), but in sentences like this it behaves as an adjective meaning broken:

• La silla está rota. = The chair is broken.

This is very common in Spanish:

• La puerta está cerrada. = The door is closed.
• La ventana está abierta. = The window is open.

So although it comes from a participle, in this sentence it is best understood as describing the chair’s state.

A broad pronunciation guide would be:

Si es-ta see-ya es-TA RO-ta, me see-EN-to en la O-tra.

A few useful notes for Spain:

• si sounds like see
• ll in silla is usually pronounced like the y in yes in most of Spain, though some regions pronounce it differently
• j does not appear here, so there is no strong guttural sound in this sentence
• the stress falls on:
  • esTÁ
  • ROta
  • SIENto
  • Otra

Also, esta and está sound different mainly because of stress:

• ES-ta
• es-TÁ

Yes, in terms of structure that can help you understand the Spanish present tense.

Spanish present tense often covers meanings that English expresses with:

• simple present
• present continuous in some contexts
• future meaning

So me siento en la otra literally looks like I sit on the other one, but in context it often means:

• I’ll sit on the other one
• or more literally/directly: I’m sitting on the other one

In natural English, I’ll sit on the other one is usually the best translation here.