Le libraire connaît bien ce quartier et recommande toujours de bons romans.

Because libraire is a false friend.

In French, un libraire means a bookseller or a bookstore owner/worker, not a librarian.

• libraire = bookseller
• librairie = bookstore / bookshop
• bibliothèque = library
• bibliothécaire = librarian

So in this sentence, Le libraire means The bookseller or The bookstore owner, not The librarian.

French has two main verbs for to know:

• connaître = to know someone, a place, or something through familiarity
• savoir = to know a fact, information, or how to do something

Here, the sentence says the bookseller knows this neighborhood well, so French uses connaître because it is about familiarity with a place.

Examples:

• Je connais ce quartier. = I know this neighborhood.
• Je sais où il habite. = I know where he lives.
• Je sais nager. = I know how to swim.

Connaît is the third-person singular present form of connaître.

So:

• je connais = I know
• tu connais = you know
• il/elle/on connaît = he/she/one knows

In this sentence, the subject is Le libraire, which is he grammatically, so French uses connaît.

The î in connaît is part of the spelling of this verb form. It often reflects an older historical spelling and helps distinguish forms.

For learners, the main thing is simply to remember that:

• il connaît
• elle connaît

but

• je connais
• tu connais

So the accent is just part of the correct spelling of that form.

Because bien is an adverb, and in French many adverbs are placed after the conjugated verb.

So:

• connaît bien = knows well

This is very natural French word order.

Compare:

• Il parle bien français. = He speaks French well.
• Elle connaît bien Paris. = She knows Paris well.

English often puts well after the object or at the end, but French commonly keeps bien right after the verb.

Because quartier is a masculine singular noun that begins with a consonant sound.

French uses:

• ce before masculine singular nouns starting with a consonant sound
• cet before masculine singular nouns starting with a vowel or mute h
• cette for feminine singular nouns

So:

• ce quartier = this neighborhood
• cet hôtel = this hotel
• cette rue = this street

Since quartier starts with qu-, you use ce.

Toujours means always.

In this sentence:

• recommande toujours = always recommends

French often places adverbs like toujours after the conjugated verb:

• Il recommande toujours...

That is the normal position here.

Compare:

• Elle arrive toujours en avance. = She always arrives early.
• Nous mangeons toujours ici. = We always eat here.

This is a very common French pattern.

Normally, the plural indefinite article is des:

• des romans = some novels

But when an adjective comes before the plural noun, des usually becomes de:

• des romans
• de bons romans

So:

• Il recommande des romans. = He recommends novels / some novels.
• Il recommande de bons romans. = He recommends good novels.

This happens because bons comes before romans.

Important note: in everyday speech, some speakers may still say des bons romans, but in standard written French, de bons romans is the expected form.

Because it describes romans, which is plural.

In French, adjectives usually agree with the noun they describe in gender and number.

• un bon roman = a good novel
• de bons romans = good novels

Here:

• romans is masculine plural
• so bon becomes bons

Because de here is not always translated as of or some in a direct, word-for-word way.

In de bons romans, the de is mainly there because of the grammar rule after a plural adjective before the noun. In English, we usually just say:

• good novels
• or sometimes some good novels

So the French structure does not always match English word for word.

Yes.

In this sentence, recommande has a direct object:

• recommande de bons romans = recommends good novels

But you can also say:

• Il recommande de bons romans à ses clients. = He recommends good novels to his customers.

So the pattern can be:

• recommander quelque chose
• recommander quelque chose à quelqu’un

Here, the sentence simply leaves out the person receiving the recommendation.

Mostly, yes, in this kind of sentence.

Quartier commonly means:

• neighborhood
• district
• area of a town or city

So ce quartier is this neighborhood or this area.

Depending on context, quartier can also have other meanings, but neighborhood/district is the normal one here.

It sounds natural and idiomatic.

It has a very typical French structure:

• Le libraire = the subject
• connaît bien ce quartier = knows this neighborhood well
• et recommande toujours de bons romans = and always recommends good novels

It is the kind of sentence you could easily see in a textbook, a story, or a description of a local bookseller.