Ammainiamo la vela ora.

Ammainiamo comes from the verb ammainare, which means to lower in a nautical sense, especially for sails or flags.

Grammatically, ammainiamo is the 1st person plural form (noi) of the present tense:

• io ammaino
• tu ammaini
• lui/lei ammaina
• noi ammainiamo
• voi ammainate
• loro ammainano

So literally, it is the we form.

It can mean either one, depending on context.

In Italian, the noi form of the present tense is also used for the 1st person plural imperative, meaning let's ...

So:

• Ammainiamo la vela ora. can mean We are lowering the sail now in the right context.
• But very often, especially as a stand-alone sentence, it means Let's lower the sail now.

This is normal in Italian:

• Andiamo! = Let's go!
• Mangiamo! = Let's eat!
• Ammainiamo la vela! = Let's lower the sail!

Italian often omits subject pronouns because the verb ending already tells you who the subject is.

Here, -iamo clearly shows noi (we), so noi is unnecessary:

• Ammainiamo la vela ora. = natural
• Noi ammainiamo la vela ora. = possible, but more emphatic

You would usually add noi only if you want contrast or emphasis:

• Noi ammainiamo la vela, voi preparate le corde. = We lower the sail, you prepare the ropes.

Italian uses the definite article much more often than English does.

So la vela literally means the sail, and this is the normal way to say it here. Even when English might say lower sail in a very compressed style, Italian normally wants the article:

• ammainare la vela
• alzare la bandiera
• aprire la porta

Leaving out the article here would sound incomplete or unnatural in standard Italian.

Ammainare is a fairly specific verb. It is mainly used for lowering sails, flags, or similar things.

So it is more specialized than a general verb like:

• abbassare = to lower / to bring down
• calare = to lower / to let down

For example:

• ammainare la vela = lower the sail
• ammainare la bandiera = lower the flag

So this sentence sounds specifically nautical.

Yes, it is natural, especially in a nautical or instructional context.

It sounds like:

• a command to a group
• a decision made by a crew
• a practical instruction during sailing

Because of ora, it feels immediate:

• Ammainiamo la vela ora. = Let's lower the sail now.

In everyday conversation outside sailing, you would not hear ammainare very often.

Yes. Ora is fairly flexible.

These are all possible:

• Ammainiamo la vela ora.
• Ora ammainiamo la vela.
• Ammainiamo ora la vela.

The most natural choice depends on what you want to emphasize:

• Ora ammainiamo la vela. = emphasis on now
• Ammainiamo la vela ora. = very natural, especially in speech
• Ammainiamo ora la vela. = a bit more marked or formal in feel

A helpful approximation is:

am-mai-NYAH-mo

A few details:

• mm is a true double consonant, so hold it slightly longer than a single m
• mai sounds like my
• niamo contains nia, which sounds like nyah

The stress is on:

• ammaiNIÀmo

So the stressed syllable is the nia part.

The ending -iamo marks the 1st person plural (we) in many present-tense verbs.

For -are verbs like ammainare, the noi ending is -iamo:

• parlare → parliamo
• guardare → guardiamo
• ammainare → ammainiamo

This same form is also used for let's ... commands, which is why ammainiamo can mean let's lower.

You probably could be understood, but ammainiamo la vela is the more precise and idiomatic nautical expression.

Compare:

• ammainare la vela = specifically lower the sail
• abbassare = lower in a general sense

So if you are talking about sailing, ammainare is the better choice.

It is neutral in tone. The sentence itself is not especially formal or informal.

What gives it its flavor is the situation, not the grammar:

• on a boat, it sounds like a practical instruction
• in a textbook, it sounds technical or nautical
• in normal daily life, it would sound unusual only because the topic is unusual

So the grammar is ordinary, but the vocabulary is specialized.