Il calcare resta nell'ugello.

Because calcare is being used here as a noun, and Italian often uses the definite article where English may or may not.

• il calcare = the limescale / limescale
• In this kind of sentence, Italian normally sounds more natural with the article.

Also, the article helps show that calcare here is a noun, not the verb calcare (to tread on, to press, etc.).

In this context, calcare means limescale: the chalky mineral deposit that builds up in appliances, pipes, kettles, shower heads, nozzles, and similar places.

Depending on context, calcare can also refer more generally to limestone or calcareous material, but in everyday household or mechanical contexts, limescale is the most likely meaning.

Resta comes from the verb restare, which means to remain, to stay, or to be left.

So in this sentence, resta suggests that the limescale remains in the nozzle, rather than passing through or being removed.

It is the:

• 3rd person singular
• present tense

So:

• (il calcare) resta = (the limescale) remains / stays

Yes, often you could.

• resta = remains / stays
• rimane = remains / stays

In many contexts they are very close in meaning. Restare and rimanere overlap a lot.
However, restare can sound a bit more straightforward or practical in everyday usage, especially in simple descriptions.

So:

• Il calcare resta nell'ugello.
• Il calcare rimane nell'ugello.

Both are grammatical and natural, though the original sentence is perfectly fine as it is.

Because Italian usually combines certain prepositions with definite articles.

Here:

• in + l' becomes nell'

So:

• in + l'ugello → nell'ugello

This is called an articulated preposition.

Similar examples:

• in + il = nel
• in + lo = nello
• in + la = nella
• in + i = nei
• in + gli = negli
• in + le = nelle

Because ugello is a masculine singular noun beginning with a vowel.

For masculine singular nouns:

• before most consonants: il
• before a vowel: l'

So:

• il tubo
• l'ugello

Then, after in, that becomes:

• in + l'ugello → nell'ugello

Ugello means nozzle.

It can refer to the part of a device where liquid, air, steam, or spray comes out, for example in:

• a spray bottle
• a coffee machine
• a hose
• a fuel injector
• a cleaning device

So nell'ugello means in the nozzle.

Because the subject is il calcare, which is grammatically singular.

Even though limescale may refer to a substance or buildup made of many particles, Italian treats calcare here as a singular mass noun.

So:

• il calcare resta = singular
• not restano

Yes. It follows a very normal pattern:

• Il calcare = subject
• resta = verb
• nell'ugello = prepositional phrase

So it is basically:

Subject + Verb + Place

This is standard, neutral word order in Italian.

Yes, but the original is the most neutral.

For example:

• Nell'ugello resta il calcare.

This is possible, but it gives more emphasis to nell'ugello or sounds more marked, depending on context.

For a simple factual statement, Il calcare resta nell'ugello is the most straightforward version.

Yes. Calcare can also be an infinitive verb meaning things like to tread on, to press, or in some contexts to emphasize strongly.

That can confuse learners at first. But in this sentence, it is clearly a noun because:

• it has the article il
• it functions as the subject of the sentence

So here:

• il calcare = the limescale

not:

• calcare = to tread/press

It is the present indicative: resta.

In Italian, the present tense can express:

• a general fact
• something happening now
• a habitual or repeated situation

So this sentence could mean something like:

• limescale remains in the nozzle
• limescale stays in the nozzle
• limescale gets left in the nozzle

The exact English wording depends on the context, but the Italian present tense is very natural here.

A simple pronunciation guide is:

eel kal-KA-re RES-ta nel-LOO-JEL-lo

A few notes:

• calcare has the stress on -ca-
• resta has the stress on res-
• ugello has the stress on -gel-
• the g in ugello sounds like the j in jam

A more approximate IPA transcription is:

[il kalˈkaːre ˈrɛsta nelˈluˈdʒɛllo]

Sometimes yes, but it is slightly different.

• nell'ugello = in the nozzle
• dentro l'ugello = inside the nozzle

Dentro is a bit more explicit about being physically inside.
Nell'ugello is the more neutral and natural choice in many technical or descriptive sentences.

So the original sentence sounds concise and idiomatic.