Au rond-point, nous restons prudents jusqu’à ce qu’une voiture s’arrête au passage piéton.

Au rond-point means at the roundabout.

Au is the contraction of à + le:

• à le rond-point → au rond-point

French very often uses à for location in expressions like this, and rond-point is masculine, so à + le becomes au.

French often puts a place expression at the beginning of the sentence to set the scene:

• Au rond-point, nous restons prudents...
• At the roundabout, we stay cautious...

The comma helps show that this is the setting or context. It is similar to starting an English sentence with At the roundabout...

Nous restons prudents means we remain cautious or we stay cautious.

That is slightly different from nous sommes prudents, which simply means we are cautious.

Using rester here emphasizes continuing in that state:

• rester prudent = to stay/remain cautious

So the sentence is really expressing ongoing caution until something happens.

Because it agrees with nous.

In this sentence, prudents describes nous, so it must match in number:

• je reste prudent = singular masculine
• nous restons prudents = plural masculine or mixed group
• nous restons prudentes = plural feminine group

So prudents is plural because nous is plural.

Jusqu’à ce que means until in the sense of until something happens.

It introduces a clause with its own verb:

• jusqu’à ce qu’une voiture s’arrête = until a car stops

This is a very common French structure. A useful pattern is:

• jusqu’à ce que + subjunctive verb

So here it is not just a simple preposition; it introduces the event that marks the end point.

Yes. After jusqu’à ce que, French normally uses the subjunctive.

So:

• infinitive: s’arrêter
• present subjunctive, elle / une voiture: s’arrête

That is why the sentence has:

• jusqu’à ce qu’une voiture s’arrête

For many -er verbs, the il/elle subjunctive form looks the same as the ordinary present, so the important clue is the grammar after jusqu’à ce que.

Because s’arrêter means to stop.

Compare:

• arrêter quelque chose = to stop something
• s’arrêter = to stop / come to a stop

Examples:

• Le policier arrête la voiture. = The police officer stops the car.
• La voiture s’arrête. = The car stops.

So in your sentence, the car is stopping by itself, which is why French uses s’arrêter.

This is because of elision.

When que comes before a word starting with a vowel sound, it usually drops the final e:

• que une → qu’une

So:

• jusqu’à ce que une voiture s’arrête becomes
• jusqu’à ce qu’une voiture s’arrête

This is very common in French:

• qu’il
• qu’elle
• qu’on
• qu’une

Une voiture means a car, so it refers to any car, not a specific one already identified.

That fits the meaning well: at a roundabout, you stay cautious until some car / a car stops at the crossing.

If it said la voiture, it would usually suggest a particular car already known from the context.

It means at the pedestrian crossing or at the crosswalk.

• passage piéton = pedestrian crossing / crosswalk
• au passage piéton = at the crosswalk

Again, au is à + le, because passage is masculine:

• à le passage piéton → au passage piéton

Yes, passage piéton is a standard and very common term for pedestrian crossing / crosswalk.

Depending on region or context, you may also hear more formal or technical terms, but passage piéton is the everyday expression learners should know.

A careful pronunciation guide would be roughly:

Au rond-point, nous restons prudents jusqu’à ce qu’une voiture s’arrête au passage piéton.

A few things to notice:

• nous restons: the s in nous links to the next word, so you often hear something like nou-restons
• jusqu’à ce qu’une: this flows together very smoothly
• une voiture s’arrête: s’arrête begins with a vowel sound, so the whole group is linked tightly
• final written consonants are often not pronounced unless there is liaison

You do not need to pronounce every written letter separately; French is much more connected in speech than English.

Yes. Even though nous literally means we, French sometimes uses it in a general or instructional way, especially in educational, safety, or explanatory contexts.

So this sentence can mean:

• we stay cautious but in context it may feel like
• we should stay cautious
• you stay cautious
• one stays cautious

The exact English wording depends on the kind of text it comes from.