Il timer mostra il conto alla rovescia.

Yes. Timer is very commonly used in Italian as a loanword from English, especially for devices, apps, appliances, and digital displays.

It is normally treated as a masculine singular noun, so the article is il:

• il timer
• i timer

Even though the word comes from English, the grammar around it is Italian.

Because timer begins with a normal consonant sound, t, and masculine singular nouns of that type usually take il.

Compare:

• il timer
• il telefono
• il tavolo

You use lo with certain masculine nouns beginning with sounds like z, s + consonant, gn, ps, etc.:

• lo zaino
• lo studente
• lo psicologo

So il timer is the expected form.

Mostrare is the infinitive, meaning to show.

In the sentence, the verb has to agree with the subject il timer, which is third person singular, so the correct present-tense form is mostra:

• mostrare = to show
• mostra = shows / is showing

So:

• Il timer mostra... = The timer shows...

Yes. In Italian, the simple present often covers both ideas, depending on context.

So Il timer mostra il conto alla rovescia can mean:

• The timer shows the countdown
• The timer is showing the countdown

If you really want to stress the ongoing action, Italian can use stare + gerundio, for example sta mostrando, but with screens and devices the simple present is very common and natural.

Yes, absolutely. Mostrare is very normal for screens, apps, timers, phones, websites, and other devices.

For example:

• Il telefono mostra un messaggio
• Lo schermo mostra l’ora
• Il timer mostra il conto alla rovescia

So this use is completely natural.

Because il conto alla rovescia is the direct object of the sentence, and conto is a masculine singular noun.

So the structure is:

• Il timer = the subject
• mostra = the verb
• il conto alla rovescia = the object

Italian uses definite articles very regularly, often more regularly than English does. Here, il is simply part of the noun phrase il conto alla rovescia.

It is a fixed expression meaning countdown.

Literally, it is something like count in reverse or reverse counting, but in real Italian you should learn conto alla rovescia as a set phrase.

So:

• un conto alla rovescia = a countdown
• il conto alla rovescia = the countdown

Alla is the contraction of a + la.

In this sentence it appears inside the fixed expression alla rovescia, which means backwards, in reverse, or the other way around.

So:

• a + la = alla
• alla rovescia = in reverse / backwards

That is why conto alla rovescia means countdown.

In alla rovescia, the form is feminine singular: rovescia.

For most learners, the best approach is to treat alla rovescia as a fixed expression meaning in reverse / backwards and memorize it as a whole.

So instead of analyzing it word by word every time, it is more useful to learn:

• conto alla rovescia = countdown
• mettere al rovescio / alla rovescia can appear in other expressions meaning reversed or backwards

Yes, but the meaning changes slightly.

• il conto alla rovescia = the countdown, a specific one
• un conto alla rovescia = a countdown, any one

In your sentence, il suggests a particular countdown, probably the one visible on the timer.

So both are grammatical, but they are not identical.

It is the most neutral and normal word order:

Subject + Verb + Object

• Il timer = subject
• mostra = verb
• il conto alla rovescia = object

So this sentence is very straightforward.

Italian can change word order for emphasis, but this version is the standard, neutral one.

Sometimes, yes, if the context is already clear.

For example, if everyone already knows you are talking about the timer, you could say just:

• Mostra il conto alla rovescia.

Italian often omits subject pronouns, but here il timer is a full noun, not a pronoun. Keeping it makes the sentence clear and explicit.

A rough English-style guide is:

eel TAI-mer MO-stra eel KON-to AL-la ro-VESH-sha

A few useful points:

• il sounds like eel
• timer in Italian is usually pronounced close to the English word, but fitted into Italian pronunciation
• mostra has stress on mo
• conto has stress on con
• rovescia has stress on ve

So the rhythm is:

Il TAImer MOs-tra il CONto alla roVEScia