Si le clignotant ne fonctionne plus, il vaut mieux freiner tôt.

In this sentence, le clignotant means the turn signal / indicator on a vehicle.

A useful thing to know is that clignotant comes from the idea of blinking or flashing. So in other contexts, it can also describe something flashing, but in driving language it commonly refers to the signal light itself.

Examples:

• mettre le clignotant = to put on your turn signal
• le clignotant gauche = the left indicator

French usually needs an article where English often does too, and sometimes even where English does not.

So le clignotant means the turn signal. In a sentence like this, French normally does not leave the noun bare.

Compare:

• Le moteur est en panne. = The engine is broken / the engine has failed.
• Le clignotant ne fonctionne plus. = The turn signal no longer works.

Even when speaking generally, French often keeps the article with concrete nouns.

Ne ... plus means no longer or not anymore.

It wraps around the conjugated verb:

• ne fonctionne plus

So:

• fonctionne = works / is working
• ne fonctionne plus = no longer works

This is a very common pattern:

• Je ne sais plus. = I don’t know anymore.
• Il ne veut plus venir. = He doesn’t want to come anymore.

In spoken French, people often drop ne:

• Le clignotant fonctionne plus.

But in standard written French, you should keep ne.

Fonctionner means to function, to operate, or to work for a device, machine, or system.

That makes it a very natural verb for something mechanical like a turn signal.

You may also hear marcher in everyday speech:

• Le clignotant ne marche plus.

That is also common and natural in conversation. But fonctionner is a bit more neutral and slightly more formal or technical.

Si is the normal French word for if when introducing a condition.

Here it introduces the condition:

• Si le clignotant ne fonctionne plus = if the turn signal no longer works

This is a standard if-clause structure in French.

A very important point for English speakers: after this kind of si, French does not use the future in the same way English sometimes does. So French says:

• Si le clignotant ne fonctionne plus...

not:

• Si le clignotant ne fonctionnera plus... for this meaning

Because French normally uses the present tense after si for a real or possible condition.

So:

• Si le clignotant ne fonctionne plus, ...

This is the normal pattern for something like:

• If the signal doesn’t work anymore, ...

French often uses:

• si + present, then a main clause in the present, future, or imperative, depending on meaning

Examples:

• Si tu as faim, mange. = If you’re hungry, eat.
• Si tu viens, je serai content. = If you come, I’ll be happy.
• Si ça ne marche pas, il faut recommencer. = If that doesn’t work, you have to start again.

In your sentence, the main clause is also in the present because it gives general advice.

Il vaut mieux is a very common expression meaning it is better or it’s best.

It comes from the verb valoir (to be worth), but as a whole expression you should learn it as an idiom:

• il vaut mieux + infinitive

So:

• il vaut mieux freiner tôt = it is better to brake early

It is often used to give advice in a neutral, general way.

Examples:

• Il vaut mieux partir maintenant. = It’s better to leave now.
• Il vaut mieux attendre. = It’s better to wait.

This il is an impersonal or dummy subject. It does not refer to a person or object.

French often requires a subject, even when English uses a more abstract structure.

So in:

• il vaut mieux freiner tôt

the il is just part of the fixed expression il vaut mieux.

It works a bit like:

• Il faut partir. = It is necessary to leave.
• Il est important de comprendre. = It is important to understand.

The il is grammatical, not meaningful on its own.

Because after il vaut mieux, French commonly uses an infinitive to express a general action that is advisable.

So:

• il vaut mieux freiner tôt = it is better to brake early

This is the same pattern as:

• Il vaut mieux attendre.
• Il vaut mieux vérifier.

There is also another structure:

• Il vaut mieux que + subjunctive

That is used when you want to mention a specific subject:

• Il vaut mieux que tu freines tôt. = It’s better that you brake early.

But in your sentence, the more general infinitive structure is the natural choice.

Tôt means early.

In this sentence, freiner tôt means to brake early or to start braking sooner rather than later.

It is an adverb, so it modifies the verb freiner.

A couple of related words:

• tôt = early
• plus tôt = earlier / sooner
• tard = late

Examples:

• Je me lève tôt. = I get up early.
• Il faut partir plus tôt. = You need to leave earlier.

Also note the accent: tôt has a circumflex accent.

Yes. Mieux vaut freiner tôt is correct and very natural.

It means the same thing as:

• Il vaut mieux freiner tôt

Both are common. The version with mieux vaut is often a bit more compact and direct.

Compare:

• Il vaut mieux freiner tôt.
• Mieux vaut freiner tôt.

You will see both in French. For a learner, it is useful to recognize that they are equivalent in meaning.

It sounds like general advice.

The structure:

• Si ..., il vaut mieux ...

does not sound like a sharp command. It sounds more like a recommendation based on a situation.

So it is softer than:

• Freinez tôt ! = Brake early!
• Il faut freiner tôt. = You must / have to brake early.

Using il vaut mieux makes the sentence sound practical and advisory rather than forceful.