La validité est de deux ans.

French usually needs an article before a noun in cases where English often does not.

So la validité means the validity. In French, saying just validité by itself would usually sound incomplete in a normal sentence.

Also, validité is a feminine singular noun, so the article is la.

You generally learn the gender together with the noun: la validité.

There is not always a perfect rule, but many nouns ending in -ité are feminine, such as:

• la possibilité
• la qualité
• la nationalité

So la validité follows a very common pattern.

In French, when you state a measurement, quantity, or duration after être, you often use de.

So:

• La validité est de deux ans.
• La durée est de trois heures.
• Le prix est de 20 euros.

Without de, est deux ans would sound wrong here.

A useful way to think about it is:

• est de + amount/measurement

Deux ans is the duration: two years.

• deux = two
• ans = years

Together, they tell you how long the validity lasts.

Because it is a duration expression, there is no article before deux ans.

Because the number is deux, and anything above one normally takes the plural in French.

So:

• un an = one year
• deux ans = two years
• trois ans = three years

Notice that an becomes ans in the plural.

Both ans and années can mean years, but ans is the more usual word in straightforward counting or duration expressions.

So with a simple time length, French normally says:

• deux ans
• trois ans
• vingt ans

Années is often used when the speaker wants to emphasize the span of time, describe the years more fully, or speak in a more literary or expressive way.

For this sentence, deux ans is the normal and natural choice.

Yes. A few natural alternatives are:

• La durée de validité est de deux ans.
• Ce document est valable deux ans.
• Cette garantie est valable deux ans.
  (if you are talking about a warranty or guarantee)

The original sentence is correct, but in some contexts la durée de validité may sound a little more explicit.

It is correct and fairly neutral, but it can sound a bit administrative or formal, especially in official contexts like:

• documents
• permits
• subscriptions
• certificates
• warranties

In everyday conversation, French speakers might more often say something like:

• C’est valable deux ans.
• Il est valable deux ans.
• Elle est valable deux ans.

depending on what is being described.

A simple pronunciation guide is:

La validité est de deux ans
la va-lee-dee-tay eh duh duh-zahn

A few helpful points:

• validité ends with a clear -té sound: tay
• est de often flows together smoothly in speech
• in deux ans, the x in deux links to the vowel in ans, so you hear a z sound: deu-zans

That linking is called liaison, and it is normal here.

A very useful pattern is:

[noun] + est de + [number] + [unit]

Examples:

• La validité est de deux ans.
• Le prix est de 15 euros.
• La longueur est de 10 mètres.
• La durée est de 30 minutes.

This pattern is common when giving factual information about:

• duration
• price
• length
• weight
• size
• quantity