Es mejor que no usemos el ascensor si está averiado.

Because es mejor que normally triggers the subjunctive.

In this sentence, Es mejor que no usemos el ascensor... means something like It’s better that we not use the lift... / We’d better not use the lift... It expresses a recommendation or judgment, not a simple statement of fact.

• usamos = present indicative: we use / we are using
• usemos = present subjunctive: that we use

So after es mejor que, Spanish uses the subjunctive:
Es mejor que + subjunctive

Usemos is the first person plural present subjunctive of usar.

A simple way to form the present subjunctive is:

1. Start with the yo form of the present indicative: uso
2. Remove the -o
3. Add the subjunctive endings

For -ar verbs, the endings are:

• yo: -e
• tú: -es
• él/ella/usted: -e
• nosotros/nosotras: -emos
• vosotros/vosotras: -éis
• ellos/ellas/ustedes: -en

So:

• yo use
• tú uses
• él/ella use
• nosotros usemos
• vosotros uséis
• ellos usen

Because the sentence follows the pattern:

es mejor que + clause

That que links the main idea to the subordinate clause:

• Es mejor = It is better
• que no usemos el ascensor = that we don’t use the lift

So que here means that.

Without que, you would normally need a different structure, such as the infinitive:

• Es mejor no usar el ascensor...

Both are possible, but they are built differently.

Yes, absolutely. That is very natural too.

There are two common ways to say this idea:

1. Es mejor que no usemos el ascensor si está averiado.
2. Es mejor no usar el ascensor si está averiado.

The difference is mainly structural:

• es mejor que + subjunctive is a full clause: it’s better that we don’t use...
• es mejor + infinitive is more general: it’s better not to use...

In many situations, both mean almost the same thing. The version with usemos feels a bit more explicitly about us/we, while no usar can sound slightly more general.

Because in Spanish, no usually goes directly before the verb it negates.

So:

• no usemos = let’s not use / that we not use

Here, no is negating the action of using the lift.

This is the normal position in Spanish:

• No quiero ir.
• No está abierto.
• Es mejor que no usemos el ascensor.

Because after si meaning if, Spanish normally uses the indicative for real or possible conditions.

So:

• si está averiado = if it is broken / if it’s out of order

Spanish does not normally use the present subjunctive after si in this kind of sentence.

Common pattern:

• Si llueve, nos quedamos en casa.
• Si está averiado, no lo usamos.

So está is correct because this is a normal, real condition.

Averiado means broken, out of order, or not working properly, especially for machines, devices, or systems.

So el ascensor está averiado means:

• the lift is broken
• the lift is out of order

It is a very natural word for things like:

• un ascensor averiado
• un coche averiado
• una lavadora averiada

For machines, averiado is often more idiomatic than a literal word like roto.

Because averiado describes the current condition or state of the lift.

Spanish often uses estar + past participle/adjective for states or conditions:

• está cerrado = it is closed
• está abierto = it is open
• está averiado = it is broken / out of order

Here, the idea is not defining what the lift is by nature, but describing its current state.

Because Spanish usually omits subject pronouns when the verb already makes the subject clear.

Usemos already tells you the subject is we (nosotros/nosotras), so nosotros is not necessary.

You could say:

• Es mejor que nosotros no usemos el ascensor...

But that would usually sound more emphatic, for example if you want to contrast we with someone else.

Most of the time, the version without the pronoun is more natural.

Yes, ascensor is the normal word in Spain for lift/elevator.

In much of Latin America, you will also hear elevador. Both are understood in many places, but for Spanish from Spain, ascensor is the standard choice.

So for Spain-focused Spanish, this sentence sounds very natural.

Yes. You can move the si clause to the front:

• Si está averiado, es mejor que no usemos el ascensor.

This means the same thing as:

• Es mejor que no usemos el ascensor si está averiado.

The difference is mainly one of emphasis:

• starting with Si está averiado... highlights the condition first
• starting with Es mejor... highlights the recommendation first

Both are correct and natural.

Because está is a form of the verb estar, and it is written with a written accent on the final a.

Examples:

• está = he/she/it is
• están = they are

This accent is simply part of the correct spelling of the verb form. It also helps distinguish it from other short words that might otherwise look similar.

So in this sentence, si está averiado is the correctly spelled form.