Learn Hardcore French: Le samedi où le festival commence, le village est plein de musique et de couleurs. - On the Saturday when the festival begins, the village is full of music and colors.

Le samedi = the Saturday (either a specific one, or “on Saturdays” in general, depending on context).
Samedi on its own often means this Saturday (the coming one).

Here, Le samedi où le festival commence means “The Saturday when the festival begins” (probably the particular Saturday that marks the opening of the festival, maybe every year). Using le matches the idea of a definite, identified day linked to the festival.

If you said simply Samedi, le village est plein…, it would more likely mean “This Saturday, the village is full…” (a one‑time, upcoming event).

Why do we use où here? I thought où meant “where,” not “when.”

In French, où can refer to:

a place:
- Le village où j’habite = the village where I live
a time:
- Le jour où il est arrivé = the day when he arrived

Here, où is a relative pronoun referring back to le samedi (a time expression):

Le samedi où le festival commence
= The Saturday when the festival begins.

So in relative clauses after words of time (jour, année, moment, époque, samedi, etc.), French often uses où where English uses when.

Could we say le samedi quand le festival commence instead of le samedi où le festival commence?

No, that sounds wrong to native speakers.

où is the correct relative pronoun after a noun of time:
- Le samedi où le festival commence
- L’année où elle est partie
quand is a conjunction, not a relative pronoun. It introduces a time clause by itself:
- Quand le festival commence, le village est plein…

So either:

Le samedi où le festival commence, le village est plein… (relative clause modifying le samedi), or
Quand le festival commence, le village est plein… (independent time clause)

…but not le samedi quand le festival commence.

Can I rewrite the sentence with quand instead of où?

Yes, but you have to change the structure:

Original: Le samedi où le festival commence, le village est plein…
With quand: Quand le festival commence, le village est plein de musique et de couleurs.

This version no longer singles out that Saturday explicitly; it just says “When the festival begins, the village is full…”. The meaning is very close, but the focus shifts from the specific Saturday to the moment of beginning in general.

Why is the verb commence in the present tense and not in the future (commencera)?

French often uses the simple present to describe:

general truths or repeated events
scheduled events (timetables, programmes, festivals, etc.)

Here, Le samedi où le festival commence can mean something like:

On the Saturday when the festival (usually / always) begins…
On the Saturday when the festival begins (every year)…

English also often uses the present for timetables:

The festival starts on Saturday.

If you said Le samedi où le festival commencera, you would be talking about one future occurrence (a particular year), not the regular, descriptive situation.

How does plein de work? Why is it plein de musique and not plein de la musique?

plein de + noun is a very common structure meaning “full of” or “lots of”:

Le village est plein de musique. = The village is full of music.
La boîte est pleine de chocolat. = The box is full of chocolate.

Key points:

No article after “de” in the neutral, general sense:
- plein de musique, like beaucoup de musique, trop de musique
  Not: plein de la musique (unless you are specifying the particular music already mentioned: plein de la musique que tu aimes, which is more advanced/marked).
plein agrees with the subject, not with what follows de (see next question).

Should plein agree with le village or with musique?

plein agrees with the subject, not with the noun after de.

Subject: le village → masculine singular → plein
- Le village est plein de musique.

More examples:

La salle est pleine de musique.
Subject: la salle → feminine singular → pleine
Les rues sont pleines de monde.
Subject: les rues → feminine plural → pleines
Les villages sont pleins de musique.
Subject: les villages → masculine plural → pleins

The noun after de does not affect the ending of plein.

Why is musique singular but couleurs is plural?

Because French treats these concepts differently:

la musique is usually a mass noun (something continuous, not counted: “music in general”). In French we normally use it in the singular when we mean “there is music”.
- Il y a de la musique. = There is music.
- plein de musique = full of music.
les couleurs is naturally countable: you think of many different colours (banners, clothes, lights, etc.), so the plural feels more natural:
- plein de couleurs = full of colours / very colourful.

So plein de musique et de couleurs = “full of music and (lots of) colours.”

Why is there no article before musique and couleurs? Why not de la musique et des couleurs?

Two things are happening:

plein de + noun usually behaves like a quantity expression, similar to:
- beaucoup de musique
- trop de couleurs
With these, you normally have de + noun with no article in the general sense:
- plein de musique
- plein de couleurs
If you say de la musique / des couleurs, you are using the partitive / indefinite plural; that’s also possible in some contexts, but here plein de + noun (no article) is the standard, idiomatic pattern.

So plein de musique et de couleurs is the most natural formulation.
plein de la musique et des couleurs would sound strange or at least very marked, as if you were emphasising some very specific music and colours already identified.

Can I change the word order? For example, can I put the time part at the end of the sentence?

Yes, you can move the time clause:

Original:
Le samedi où le festival commence, le village est plein de musique et de couleurs.
Alternative:
Le village est plein de musique et de couleurs le samedi où le festival commence.

Both are correct. Putting Le samedi où… at the beginning gives extra emphasis to that particular Saturday. Placing it at the end sounds a bit more neutral and informational.

In writing, you normally keep the comma when the subordinate clause comes first; when it comes last, French often omits the comma:

Le samedi où le festival commence, …
… le samedi où le festival commence.