En el ordenador de la biblioteca, la impresora no funciona si el escáner está encendido.

This opening phrase sets the location or context: it means on the library computer.

Spanish often puts this kind of information first to frame the whole sentence. So the sentence is basically saying:

On the library computer, the printer doesn't work if the scanner is turned on.

The comma helps separate this introductory context from the main statement.

En is the normal preposition for meaning on a computer, device, system, website, app, etc.

So:

• en el ordenador = on the computer
• sobre el ordenador would usually mean physically on top of the computer, which is not the meaning here.

In technology contexts, Spanish often uses en where English uses on.

Both mean computer, but ordenador is the usual word in Spain, while computadora or computador is more common in much of Latin America.

Since this is Spanish from Spain, ordenador is exactly what you would expect here.

It describes el ordenador.

So:

• el ordenador de la biblioteca = the library's computer / the computer in the library

It does not describe la impresora. The phrase is grouped like this:

[En [el ordenador de la biblioteca]], [la impresora no funciona]...

Spanish uses definite articles much more often than English.

So even where English might say:

• the printer
• or sometimes just printer in a technical statement,

Spanish usually says:

• la impresora

Here it refers to the printer associated with that computer or that situation, so the article sounds natural.

It can mean either, depending on context.

No funciona is present tense:

• doesn't work
• isn't working

In this sentence, it means that whenever the scanner is on, the printer fails to work. English could translate it either way depending on style.

Because si without an accent means if.

Compare:

• si = if
• sí = yes or indeed

So here:

• si el escáner está encendido = if the scanner is on

Because this is a real, possible condition, not a hypothetical or doubtful one.

Spanish normally uses the indicative after si for real conditions in the present:

• Si llueve, no salgo.
• Si el escáner está encendido, la impresora no funciona.

So está is correct.

The subjunctive is not used after si in this kind of basic present-time condition.

Because encendido here describes a state, not an essential characteristic.

• estar encendido = to be on / switched on
• estar apagado = to be off / switched off

Spanish uses estar for temporary states like this.

So:

• el escáner está encendido = the scanner is on

Using ser here would sound wrong.

Because encendido agrees with el escáner, which is masculine singular.

Agreement:

• el escáner está encendido
• la impresora está encendida

The adjective or participle has to match the noun in gender and number.

The comma marks the introductory phrase En el ordenador de la biblioteca as background information.

It is similar to English:

• On the library computer, the printer doesn't work if the scanner is on.

The sentence could sometimes appear without a comma in less careful writing, but with the comma it is clearer and more natural as a framed statement.

Yes. A very natural alternative is:

La impresora no funciona en el ordenador de la biblioteca si el escáner está encendido.

This keeps the same meaning, but the original version emphasizes the location first.

Spanish word order is often flexible, especially with prepositional phrases like En el ordenador de la biblioteca.

Escáner means scanner.

It has an accent mark because it is the adapted Spanish spelling of the borrowed word, and the accent shows the stress: es-CÁ-ner.

This is standard in Spanish spelling:

• escáner
• plural: escáneres

Yes. Funcionar is very general and can mean to work, to function, or to operate for machines, devices, systems, apps, and more.

So la impresora no funciona could mean:

• the printer hardware does not work,
• the printer is not responding,
• the printer setup is failing on that computer.

Spanish leaves that open unless more detail is added.

Not exactly.

• si = if
• cuando = when

Si el escáner está encendido means the printer fails under that condition. Cuando el escáner está encendido sounds more like whenever the scanner is on.

In many contexts the practical meaning is similar, but si focuses on the condition, while cuando focuses more on the time or repeated situation.

Historically it is a past participle, but in this sentence it works like an adjective describing the scanner's state.

So you can think of:

• encendido = on
• apagado = off

This is very common in Spanish with device states:

• La luz está encendida.
• El móvil está apagado.

Because the noun escáner is masculine in Spanish.

So it takes:

• el escáner
• un escáner
• el escáner está encendido

Grammatical gender in Spanish often has to be learned with the noun itself, especially with borrowed words.