Il libro del mese è un'antologia.

Because libro is a masculine singular noun that begins with a normal consonant, so it takes il.

Italian uses:

• il before most masculine singular nouns: il libro, il tavolo
• lo before special sound groups such as z, s + consonant, gn, ps, x, and similar cases: lo zaino, lo studente

So il libro is the correct form.

Del means of the here.

It is made from:

• di = of
• il = the

So:

• di + il = del

This kind of combination is very common in Italian and is called an articulated preposition.

In standard Italian, no. You normally use the contracted form:

• del mese, not di il mese

Italian regularly combines prepositions and definite articles this way:

• di + il = del
• a + il = al
• da + il = dal
• in + il = nel

So del mese is the normal and correct form.

Not always. Del can have different uses depending on context.

Here, del mese clearly means of the month.

But in other sentences, del can sometimes have a partitive meaning, something like some:

• Vorrei del pane = I would like some bread

So the meaning depends on the sentence. In Il libro del mese, it is not partitive; it expresses a relationship: the book of the month.

Because è is the verb essere in the third-person singular, meaning is.

The accent matters because:

• è = is
• e = and

So the accent helps you tell two different words apart.

Because antologia is a feminine singular noun that begins with a vowel.

The feminine indefinite article is una, but before a vowel it shortens to un':

• una storia
• un'antologia

So una antologia becomes un'antologia.

Because un and un' are not the same thing.

• un is normally the masculine singular indefinite article: un libro
• un' is the shortened form of feminine una before a vowel: un'antologia

So the apostrophe shows that una has been shortened. It is not optional here.

You can tell from a few clues:

• It uses un', which comes from feminine una
• It ends in -a, which is often a feminine ending in Italian
• Its definite singular form would be l'antologia

So the noun is feminine: un'antologia, l'antologia, le antologie.

Because grammatical gender in Italian belongs to each noun individually.

• libro is a masculine noun
• antologia is a feminine noun

In a sentence with essere, the two nouns do not have to match in gender. Each noun keeps its own gender. That is completely normal.

What matters here is that both are singular:

• Il libro = singular
• un'antologia = singular

Yes. Literally, it is the book of the month, and that is the natural Italian structure.

Italian often uses:

• noun + di/del + noun

So:

• il libro del mese = the book of the month

Depending on context, English might sometimes say book of the month without the, especially in a label or heading, but the Italian phrase here is perfectly normal.

Not in a normal full sentence.

In ordinary Italian, a specific singular count noun usually needs an article, so il libro del mese is the natural subject.

You might see Libro del mese without il in:

• titles
• headings
• labels
• very compact promotional language

But as a standard sentence, Il libro del mese è un'antologia is the correct form.

A rough English-style guide is:

eel LEE-bro del MAY-zeh eh oo-nan-to-lo-JEE-a

A few useful notes:

• libro has stress on LI
• mese sounds roughly like MAY-zeh
• è is a short eh
• antologia has stress on gì: an-to-lo-GÌ-a
• In un'antologia, the words run together smoothly in speech

A more Italian-like rhythm would be:

Il LÌ-bro del MÈ-se è un-an-to-lo-GÌ-a