Le vide-grenier est dimanche.

A vide-grenier is a kind of neighborhood sale where people sell old things they no longer want, often outdoors. In English, it is often translated as garage sale, yard sale, or sometimes flea market, depending on the context.

Literally, vide-grenier means empty-the-attic:

• vider = to empty
• grenier = attic

So the idea is: people are emptying out their attics and selling what they find.

Because it functions as a fixed compound noun. French often uses hyphens in set expressions made from multiple words that together act like one noun.

So:

• un vide-grenier = a garage sale / flea market-like sale

You should usually learn it as one complete expression rather than trying to build it word by word every time.

Le means the, so Le vide-grenier refers to a specific sale that both speakers already know about.

Compare:

• Le vide-grenier est dimanche. = The garage sale is on Sunday.
• Un vide-grenier a lieu dimanche. = A garage sale is taking place on Sunday.

So le is used because this is a particular event, not just any garage sale.

This is a very common difference between French and English.

In English, you say:

• The garage sale is on Sunday.

In French, with days of the week after être, you normally do not use a preposition:

• Le vide-grenier est dimanche.

So French says literally something like:

• The garage sale is Sunday

That is just the normal pattern here.

Because when French gives the day on which something happens, the day name often appears by itself:

• C’est lundi. = It’s Monday.
• La réunion est mardi. = The meeting is Tuesday.
• Le vide-grenier est dimanche. = The garage sale is on Sunday.

If you say le dimanche, that usually means on Sundays or every Sunday, not one specific Sunday.

Compare:

• Le vide-grenier est dimanche. = The sale is on Sunday.
• Le marché est ouvert le dimanche. = The market is open on Sundays.

French, like English, often uses the present tense for scheduled future events.

So:

• Le vide-grenier est dimanche. means a planned future event, even though the verb is present.

English does this too:

• The concert is Friday.
• My flight is tomorrow.

So this usage is completely natural.

Yes. Some alternatives are:

• Le vide-grenier a lieu dimanche.
  = The garage sale takes place on Sunday.
  This is a bit more formal.

• Il y a un vide-grenier dimanche.
  = There is a garage sale on Sunday.
  This is very common in everyday speech.

• Le vide-grenier est dimanche prochain.
  = The garage sale is next Sunday.
  This is clearer if you want to specify which Sunday.

So Le vide-grenier est dimanche is correct and natural, but it is not the only possible wording.

By itself, dimanche usually means Sunday, and the exact meaning depends on context.

For example:

• If today is Friday, dimanche will usually mean the upcoming Sunday.
• If there could be confusion, French speakers often make it clearer with:
  • ce dimanche = this Sunday
  • dimanche prochain = next Sunday

So Le vide-grenier est dimanche is natural, but it may rely on context to be fully precise.

It is masculine:

• le vide-grenier
• un vide-grenier

That is why the sentence begins with Le.

Its plural is:

• les vide-greniers

Example:

• Les vide-greniers sont populaires au printemps.

A simple pronunciation guide is:

luh veed-gruh-nyay ay dee-monsh

A more accurate French pronunciation is approximately: [lə vid gʁənje ɛ di.mɑ̃ʃ]

A few notes:

• vide sounds like veed
• grenier ends roughly like nyay
• dimanche ends with a soft sh sound

There is no special liaison to worry about here between est and dimanche in normal speech.