La decisione è unanime.

Because decisione is a noun, and in Italian nouns are very often used with an article.

Here, la decisione means the decision. Italian uses the definite article more often than English does, so in many contexts where English might be a bit more flexible, Italian still prefers the article.

• La decisione è unanime. = The decision is unanimous.

If you said just Decisione è unanime, it would sound incomplete or unnatural in standard Italian.

Yes. Decisione is a feminine singular noun, so it takes the feminine singular article la.

A useful thing to notice is that nouns ending in -e can be either masculine or feminine, so you cannot rely only on the ending. You often just have to learn the gender with the word.

• la decisione = the decision
• le decisioni = the decisions

So even though it does not end in -a, it is still feminine.

È is the third-person singular of essere, which means to be.

So:

• La decisione = the decision
• è = is
• unanime = unanimous

Together: La decisione è unanime. = The decision is unanimous.

The accent is very important because it distinguishes è from e.

• è = is
• e = and

So:

• La decisione è unanime. = The decision is unanimous.
• La decisione e il voto... = The decision and the vote...

In writing, Italian normally requires this accent.

Because unanime is a predicate adjective here: it describes the subject la decisione after the verb essere.

This works much like English:

• The decision is unanimous.
• La decisione è unanime.

In Italian, adjectives used after essere commonly come after the verb, just as in English.

You can also use unanime directly with the noun:

• una decisione unanime = a unanimous decision

So the adjective can follow the noun there too.

In the singular, unanime has the same form for both masculine and feminine.

• il voto è unanime = the vote is unanimous
• la decisione è unanime = the decision is unanimous

In the plural, it becomes unanimi:

• I voti sono unanimi.
• Le decisioni sono unanimi.

So it does agree in number, but in the singular the masculine and feminine forms happen to be identical.

The normal, neutral order is:

• La decisione è unanime.

This is the most natural way to say it in ordinary Italian.

You can change the order in special contexts for emphasis, but that is much less neutral. For example, a speaker might front unanime in literary or emphatic language, but a learner should stick with:

• subject + essere + adjective

So this sentence is a very standard pattern.

A simple pronunciation guide is:

• decisione ≈ deh-chee-ZYOH-neh
• unanime ≈ oo-NAH-nee-meh

And the whole sentence:

• La decisione è unanime.
  ≈ lah deh-chee-ZYOH-neh eh oo-NAH-nee-meh

A couple of useful notes:

• The stress in decisione is on -zio-
• The stress in unanime is on -na-
• è is pronounced like eh

Usually yes, but the most natural English translation may depend on context.

Italian often uses this kind of sentence in formal, political, legal, or meeting-related contexts. Depending on the situation, English might say:

• The decision is unanimous.
• The decision was unanimous.
• It was a unanimous decision.

So the Italian sentence is straightforward, but English may choose a slightly different phrasing depending on style.

Not with the same meaning.

• La decisione è unanime. = The decision is unanimous.
• È una decisione unanime. = It is a unanimous decision.

The second sentence is grammatically fine, but it has a different structure. It uses una decisione unanime as a noun phrase, while the original sentence uses unanime as an adjective after essere.

So both are correct, but they are not structured in the same way.

Yes, it sounds fairly neutral to formal, and it is very natural in contexts such as:

• meetings
• politics
• committees
• official statements
• journalism

For example, you might hear it after a vote or group discussion where everyone agrees.

It is not strange in everyday Italian, but it is especially common in more formal or public language.