Il portafiltro è pulito, allora prepariamo la dose.

Italian often uses the definite article where English might leave it out. Il portafiltro means the portafilter.

In this sentence, the speaker is talking about a specific portafilter already known in the situation, so il is natural. In practical instructions or café contexts, Italian still commonly keeps the article: il portafiltro, la macchina, la dose, etc.

Also, portafiltro is a masculine singular noun, so it takes il.

Portafiltro is a masculine singular noun.

It is a compound word:

• porta- = carrier/holder
• filtro = filter

So literally it is something like filter-holder, which is why in coffee vocabulary it corresponds to portafilter.

Because it is masculine singular, related words must agree with it:

• il portafiltro
• è pulito

È is the third-person singular form of essere (to be): is.

The accent is important because:

• è = is
• e = and

So:

• Il portafiltro è pulito = The portafilter is clean
• Il portafiltro e pulito would be incorrect

This accent is one of those small but very important spelling details in Italian.

Pulito is an adjective, and in Italian adjectives usually agree with the noun they describe.

Since portafiltro is:

• masculine
• singular

the adjective must also be:

• masculine
• singular

So:

• il portafiltro è pulito

Compare:

• la tazza è pulita = the cup is clean
• i portafiltri sono puliti = the portafilters are clean
• le tazze sono pulite = the cups are clean

Here allora means something like:

• so
• then
• in that case

It connects the first idea to the next one:

• Il portafiltro è pulito, allora prepariamo la dose.
• The portafilter is clean, so/then let’s prepare the dose.

In conversation, allora is very common and can have slightly different uses depending on context. Here it introduces a consequence or next step.

It can mean both, depending on context.

Prepariamo is the first-person plural form of preparare in the present tense:

• noi prepariamo = we prepare / we are preparing

But in many contexts, especially instructions or teamwork, Italian uses this form like English let’s ...:

• Prepariamo la dose. = Let’s prepare the dose.

In your sentence, that is probably the most natural interpretation:
The portafilter is clean, so let’s prepare the dose.

Italian often omits subject pronouns when they are not needed, because the verb ending already shows the subject.

Here:

• prepariamo already tells you the subject is we

So noi is unnecessary unless you want emphasis or contrast.

Compare:

• Prepariamo la dose. = We prepare / Let’s prepare the dose.
• Noi prepariamo la dose. = We prepare the dose.
  This sounds more emphatic, as if contrasting with someone else.

Again, Italian often uses the definite article more than English does.

La dose literally means the dose. In coffee context, it usually refers to the measured amount of coffee to prepare.

Even if English might sometimes say simply prepare a dose or prepare the dose depending on context, Italian naturally says preparare la dose when the dose is understood as the standard next step in the process.

Grammatically:

• dose is a feminine singular noun
• so it takes la

Yes. Not all feminine nouns end in -a.

Dose is a feminine singular noun:

• la dose
• una dose

Its plural is:

• le dosi

This is a good reminder that noun gender in Italian cannot always be guessed from the ending alone.

The comma helps separate the two parts of the sentence:

• Il portafiltro è pulito
• allora prepariamo la dose

It marks a natural pause and shows that the second part follows from the first. In English, this is similar to:

• The portafilter is clean, so let’s prepare the dose.

Punctuation in Italian is often similar to English here, though actual comma use can vary a little by style.

Yes, often you could.

• allora = so, then, in that case
• quindi = therefore, so

So:

• Il portafiltro è pulito, allora prepariamo la dose.
• Il portafiltro è pulito, quindi prepariamo la dose.

Both are possible. Quindi can sound a bit more explicitly logical; allora can feel a bit more conversational and procedural, like moving to the next step.

The sentence has two main parts:

1. Il portafiltro è pulito

   • Il portafiltro = subject
   • è = verb
   • pulito = adjective describing the subject

2. allora prepariamo la dose

   • allora = connector (so / then)
   • prepariamo = verb
   • la dose = direct object

So the pattern is:

[subject] + [to be] + [adjective], [connector] + [verb] + [object]

That makes it a very useful model for similar Italian sentences:

• La macchina è pronta, allora iniziamo.
• Il latte è caldo, allora montiamolo.

Then you would normally use the imperative, not prepariamo.

For one person:

• Il portafiltro è pulito, allora prepara la dose.

For more than one person:

• Il portafiltro è pulito, allora preparate la dose.

So the original prepariamo sounds inclusive:

• let’s prepare the dose

while prepara sounds like an instruction addressed to one person:

• prepare the dose