Bon voyage !

It is pronounced roughly bohn vwa-yahzh.

A more precise guide:

• bon: the on is a nasal sound, so you do not fully pronounce an n
• voyage: sounds like vwah-yahzh

In IPA, it is /bɔ̃ vwajaʒ/.

Because voyage is a masculine noun in French, so the adjective must agree with it.

• masculine singular: bon
• feminine singular: bonne

Since it is un voyage, you say bon voyage.

Voyage is a noun meaning a trip, journey, or travel depending on context.

Important grammar facts:

• singular: voyage
• plural: voyages
• gender: masculine

So:

• un voyage = a trip / a journey
• des voyages = trips / journeys

This expression is a fixed phrase used to wish someone well, similar to English expressions like Safe trip! or Good luck!

In French, many short wishes use just an adjective + noun without an article:

• Bon courage !
• Bonne chance !
• Bonne journée !
• Bon appétit !

So Bon voyage ! is completely natural as a set expression.

They say it when someone is about to leave for a trip or journey.

Typical situations:

• at the airport
• before someone goes on holiday
• before a long train trip
• when seeing someone off

It is a friendly way to wish the person a good trip.

It works in both formal and informal situations.

You can say it to:

• a friend
• a colleague
• a customer
• a family member
• someone you do not know very well

It is a neutral, polite expression.

In this expression, voyage is understood broadly. It can be used for many kinds of trips, especially when someone is going away.

That said, in everyday French, voyage can sometimes sound a little more like journey or travel, while voyage in Bon voyage ! is simply the standard fixed phrase to wish someone a good trip.

No. It must be Bon voyage ! because voyage is masculine.

Compare:

• bon voyage → masculine noun
• bonne journée → feminine noun
• bonne chance → feminine noun
• bon appétit → masculine noun

The adjective changes to match the gender of the noun.

In standard French typography, there is usually a space before !, ?, :, and ;.

So French normally writes:

• Bon voyage !
• Comment ça va ?

This is different from standard English punctuation, where there is no space before the exclamation mark.

Yes. It is very common in both.

You might see it:

• in a text message
• in an email
• on a card
• in a social media comment

For example:

• Tu pars demain ? Bon voyage !
• Bon voyage et profite bien de tes vacances !

So it is perfectly natural both spoken and written.