Manteniamo la promessa.

Manteniamo comes from the verb mantenere, which often means to keep, to maintain, or to uphold, depending on context.

In Manteniamo la promessa, it means keep in the sense of keep a promise.

So the sentence can mean:

• We keep the promise
• We are keeping the promise
• Let’s keep the promise

The exact meaning depends on context, because Italian allows the same form to do more than one job here.

It can be either.

Manteniamo is:

• 1st person plural present indicative = we keep / we are keeping
• 1st person plural imperative = let’s keep

This is very common in Italian. The noi form of the imperative looks exactly like the noi form of the present tense.

So:

• Manteniamo la promessa. could mean We keep the promise.
• It could also mean Let’s keep the promise.

Context tells you which one is intended.

Italian often drops subject pronouns when they are not needed.

The ending -iamo already tells you the subject is we.

So:

• Manteniamo la promessa and
• Noi manteniamo la promessa

both mean the same basic thing.

You add noi only if you want emphasis, contrast, or extra clarity:

• Noi manteniamo la promessa, loro no.
  We keep the promise, they don’t.

Italian uses articles more often than English does.

Here, la promessa means the promise, referring to a specific promise that is already known in the conversation or situation.

Italian normally says:

• mantenere una promessa = to keep a promise
• mantenere la promessa = to keep the promise

Using just promessa without an article would sound incomplete or unnatural in standard Italian.

Because la promessa refers to a specific promise.

Compare:

• Manteniamo una promessa. = We keep a promise / Let’s keep a promise.
• Manteniamo la promessa. = We keep the promise / Let’s keep the promise.

So la suggests that both speaker and listener know which promise is being talked about.

The base form is mantenere.

Its present tense is:

• io mantengo = I keep
• tu mantieni = you keep
• lui/lei mantiene = he/she keeps
• noi manteniamo = we keep
• voi mantenete = you all keep
• loro mantengono = they keep

So manteniamo is the noi form.

A useful thing to notice: this verb is not perfectly regular all the way through, so it is worth learning as a full pattern rather than guessing every form.

Yes. Mantenere una promessa is the standard and very common way to say to keep a promise.

Other common combinations are:

• mantenere la parola = to keep one’s word
• mantenere un impegno = to keep a commitment
• mantenere una promessa fatta = to keep a promise that was made

So this sentence uses a very natural collocation.

A simple pronunciation guide is:

man-te-NYA-mo la pro-MES-sa

A few notes:

• niamo in manteniamo sounds like NYA-mo
• The stress in manteniamo falls on -nia-
• The stress in promessa falls on -mes-

A rough English-friendly approximation is:

mahn-teh-NYAH-moh lah proh-MESS-sah

Yes, but the meaning changes.

• Manteniamo la promessa = We keep / Let’s keep the promise
  one specific promise
• Manteniamo le promesse = We keep / Let’s keep the promises
  more than one promise, or promises in general

So the singular and plural matter here.

Yes. Manteniamo la nostra promessa means We keep our promise or Let’s keep our promise.

Adding nostra makes ownership explicit.

Compare:

• la promessa = the promise
• la nostra promessa = our promise

Often Italian does not need the possessive if the context already makes it obvious, so la promessa can be perfectly natural on its own.

It is neutral and natural standard Italian.

Nothing in Manteniamo la promessa is especially formal, literary, or slangy. It would work in many contexts:

• everyday conversation
• speeches
• writing
• slogans or appeals

If used as a command, it can sound encouraging or persuasive:

• Manteniamo la promessa! = Let’s keep the promise!

Yes, but Manteniamo la promessa is the normal order.

Italian usually follows:

• verb + object here

You might sometimes see a different order for emphasis, but it is less neutral:

• La promessa la manteniamo.
  As for the promise, we’re keeping it.

That version sounds more emphatic or contrastive. For a basic sentence, Manteniamo la promessa is the best model to learn.