Dans ce mot, le « b » ne se prononce pas.

Dans ce mot means in this word.

• dans = in
• ce = this
• mot = word

French often puts this kind of context first: In this word, ... It sets up what the speaker is talking about before giving the main point.

It is ce mot because mot is:

• masculine
• singular
• starts with a consonant sound

The demonstratives are:

• ce
  • masculine singular noun beginning with a consonant: ce mot
• cet
  • masculine singular noun beginning with a vowel or mute h: cet homme
• cette
  • feminine singular noun: cette lettre
• ces
  • plural: ces mots

You could say ce mot-là for extra emphasis, like that word or this particular word, but plain ce mot is the normal choice here.

In French, when you refer to a letter as a thing, you usually use an article:

• le b
• le a
• le t

So le b means the letter b.

This is very natural in French. English can also do this sometimes: the b is silent.

The symbols « » are French quotation marks, often called guillemets.

So le « b » simply means the letter b is being mentioned as a character, not used as part of a word in the sentence.

You may also see French spacing conventions around them in careful writing:

• « b »

In less formal contexts, people may also use English-style quotation marks, but « » are standard in French.

This is the negative form of se prononcer in this kind of expression.

The pattern is:

• ne ... pas = not

So:

• se prononce = is pronounced / pronounces itself in a grammar sense
• ne se prononce pas = is not pronounced

In everyday modern spoken French, the ne is often dropped:

• Le b se prononce pas But in correct written French, you normally keep ne:
• Le b ne se prononce pas

Here French uses a reflexive form, se prononcer, in a way that often corresponds to English to be pronounced.

So:

• Le b ne se prononce pas = The b is not pronounced

This is a very common French structure when talking about pronunciation.

You can compare:

• Ça se dit comment ? = How is that said?
• Ce mot se prononce... = This word is pronounced...

It is not really reflexive in the everyday sense of doing something to oneself. It is more like a standard French way to express a passive idea.

Yes. On ne prononce pas le b is also correct.

It means:

• People do not pronounce the b
• more naturally in English: The b is not pronounced

The difference is mainly in style:

• Le b ne se prononce pas = more neutral, often used in explanations, dictionaries, teaching
• On ne prononce pas le b = also common, a bit more direct, with an indefinite on meaning people / one / we

Both are good French.

Yes, essentially.

If a letter ne se prononce pas, it is not pronounced, so in English we would often call it silent.

Another common French way to say this is:

• Le b est muet.

That means:

• The b is silent.

So these are close in meaning:

• Le b ne se prononce pas.
• Le b est muet.

The comma separates the introductory phrase from the main statement.

• Dans ce mot = the setting or context
• le b ne se prononce pas = the main information

So the comma works a lot like in English:

• In this word, the b is not pronounced.

It helps readability, though in some short sentences French punctuation can be somewhat flexible. Here, the comma is very natural.

prononce is pronounced approximately like:

• pro-nonss

More roughly in IPA:

• /pʁɔ.nɔ̃s/

A few important points:

• the pr is a French pr
• on is a nasal vowel, not like English on
• the final -ce sounds like ss

So se prononce sounds roughly like:

• suh pro-nonss

But the e in se is often very light in normal speech.

In this sentence, le b refers to the written letter in the word.

The idea is:

• the word contains the letter b
• but that letter is not spoken aloud in pronunciation

So the sentence is about spelling versus pronunciation: a letter is present in writing, but absent in speech.

Yes, very common.

French often explains pronunciation with patterns like:

• Le x ne se prononce pas.
• Le s final ne se prononce pas.
• Le t est muet.
• Cette lettre se prononce comme...

So Dans ce mot, le b ne se prononce pas is a very typical and useful model sentence for talking about silent letters in French.