Le livre a cinquante pages.

Le means the. It shows that we are talking about the book, not just a book in general.

• Le livre = the book
• Un livre = a book

So Le livre a cinquante pages means The book has fifty pages, while Un livre a cinquante pages would mean A book has fifty pages.

Because livre is a masculine noun in French.

French nouns have grammatical gender:

• le is used with masculine singular nouns
• la is used with feminine singular nouns

So:

• le livre = the book
• not la livre

This is grammatical gender, so it does not mean the book is actually male.

A means has.

It is the third-person singular form of the verb avoir, which means to have.

The present tense of avoir begins like this:

• j’ai = I have
• tu as = you have
• il/elle/on a = he/she/it/one has

So in Le livre a cinquante pages, a means has:

• The book has fifty pages

In speech, a and à are pronounced the same: ah.

But they mean different things:

• a = has (from avoir)
• à = to, at, in

Examples:

• Le livre a cinquante pages. = The book has fifty pages.
• Il est à Paris. = He is in Paris.

So the meaning comes from context and spelling.

French often uses avoir (to have) the same way English uses to have for possession or characteristics.

So:

• Le livre a cinquante pages = The book has fifty pages

This is very natural in French. It is the normal way to say how many pages a book has.

Cinquante means fifty.

It is usually pronounced roughly like:

• sank-ahnt

A more accurate French pronunciation is close to:

• /sɛ̃.kɑ̃t/

A few useful points:

• the first syllable has a nasal sound
• the final t is pronounced in cinquante

So cinquante pages means fifty pages.

Because the number is fifty, so there is more than one page.

In French, nouns usually take -s in the plural:

• une page = one page
• des pages = pages
• cinquante pages = fifty pages

So pages must be plural here.

No. The final s in pages is normally silent.

So pages is pronounced roughly like:

• pahzh

The plural is shown in writing, but you usually do not hear the s itself.

Because in French, after a number, you normally put the noun directly after it.

So:

• cinquante pages = fifty pages
• not cinquante de pages

This is similar to English, where we also say fifty pages, not fifty of pages.

Because normal French word order is often:

subject + verb + object/complement

Here:

• Le livre = subject
• a = verb
• cinquante pages = what the book has

So the structure is very close to English:

• The book
  • has
    • fifty pages

Usually, no important liaison is made here.

You would normally pronounce it roughly as:

• Le livre a cinquante pages
• luh leevr ah sank-ahnt pahzh

A few notes:

• livre a does not usually create a liaison
• cinquante pages also does not normally have a liaison

So you can say each part smoothly without adding an extra linking sound.

Yes. Livre can also refer to an old unit of weight, similar to pound, in some contexts.

But in modern everyday French, un livre almost always means a book.

In this sentence, because of cinquante pages, it clearly means book.

You put ne ... pas around the verb:

• Le livre n’a pas cinquante pages.

This means:

• The book does not have fifty pages.

Notice that:

• ne becomes n’ before a
• the pattern is subject + ne/n’ + verb + pas

Yes. A common alternative is:

• Il y a cinquante pages dans le livre.

This means:

• There are fifty pages in the book.

Both are correct, but they focus slightly differently:

• Le livre a cinquante pages = the book has fifty pages
• Il y a cinquante pages dans le livre = there are fifty pages in the book

The original sentence is simple and very natural.