La cottura dura otto ore.

In Italian, nouns are often used with an article where English might leave it out.

So la cottura is perfectly natural and means something like the cooking process or the cooking time/process in context.

Italian usually prefers the article with general or specific nouns much more than English does.
So:

• La cottura dura otto ore.
• literally: The cooking lasts eight hours

Leaving out la would sound less natural here.

Cottura is a noun from the verb cuocere (to cook, especially in the sense of applying heat).

It usually refers to:

• cooking
• the cooking process
• cooking time
• doneness in some contexts

So la cottura is not the action to cook as a verb, but the noun cooking/cooking process.

Compare:

• cuocere = to cook
• cucinare = to cook, to prepare food
• cottura = cooking, cooking process, cooking duration, doneness

Because Italian uses the verb durare to express duration.

• durare = to last

So:

• La cottura dura otto ore = The cooking lasts eight hours

Using essere would not work here in standard Italian.

English often says:

• It is eight hours long
• It takes eight hours
• It lasts eight hours

Italian commonly uses durare for this idea.

Dura is the third person singular present form of durare.

The subject is la cottura, which is singular, so the verb must also be singular.

Conjugation of durare in the present:

• io duro
• tu duri
• lui/lei dura
• noi duriamo
• voi durate
• loro durano

Since la cottura = it, you get dura.

Because otto means eight, and the noun must be plural: ore = hours.

• un'ora = one hour
• due ore = two hours
• otto ore = eight hours

So after any number greater than one, you use the plural noun.

Also note:

• singular: ora
• plural: ore

No. Otto is a number, and in this use it does not change for gender or number.

So you say:

• otto ore
• otto minuti
• otto giorni

The noun changes as needed, but otto stays otto.

In Italian, a duration can often be expressed without a preposition after durare.

So the most natural structure is:

• La cottura dura otto ore.

This is the normal way to say it lasts eight hours.

You may sometimes see per otto ore in other kinds of sentences, but with durare, the direct duration expression is standard and natural.

Compare:

• Il film dura due ore.
• La lezione dura un'ora.

They are similar, but not exactly the same in structure or emphasis.

• La cottura dura otto ore = The cooking lasts eight hours
• Ci vogliono otto ore di cottura = Eight hours of cooking are needed / It takes eight hours of cooking

Both can work, but the first focuses on duration, while the second focuses more on what is required.

Another very common phrase is:

• Il tempo di cottura è di otto ore.

That means The cooking time is eight hours.

Usually it refers to a specific cooking process understood from context, such as a particular dish or recipe.

For example, in a recipe or instructions:

• La cottura dura otto ore.

This would normally mean the cooking of this dish takes eight hours.

Because of the article la, it often sounds like a particular, identifiable cooking process rather than cooking in general as an abstract idea.

A few pronunciation points are especially important here:

• cottura has a double tt
• otto also has a double tt
• ore has two clear syllables: o-re

Roughly:

• la cot-TU-ra DU-ra OT-to O-re

The doubled consonants matter in Italian, so try to make the tt in cottura and otto clearly longer than a single t.

Yes, but La cottura dura otto ore is the most neutral and standard order.

Italian word order is fairly flexible, but changing it usually changes emphasis.

For example:

• La cottura dura otto ore. = neutral
• Otto ore dura la cottura. = more marked, more literary or emphatic

For everyday learning, the original order is the best one to use.