Quand la marée est basse, les enfants courent entre les dunes avec leur seau.

Quand means when. It introduces a time clause: Quand la marée est basse = When the tide is low.

In this sentence, it gives the condition in time for the main action:

• Quand la marée est basse → the time/background situation
• les enfants courent... → the main action

French often uses quand this way, just like English uses when.

In French, nouns usually need an article much more often than in English. So where English might say the tide or sometimes talk more generally about tide, French normally says la marée.

Here:

• la marée = the tide

This is very natural in French. Leaving out the article would sound incomplete.

Because here basse is not directly describing the noun inside the noun phrase; it comes after être and functions like a predicate adjective.

So:

• la marée est basse = the tide is low

This is different from a structure like:

• la basse marée = low tide

Both exist, but they are used differently:

• la marée est basse describes the state of the tide
• la basse marée names the phenomenon or stage: low tide

Because basse agrees with marée, and marée is a feminine noun.

So:

• masculine: bas
• feminine: basse

Examples:

• Le mur est bas = The wall is low
• La marée est basse = The tide is low

French adjectives often change form to match the gender and number of the noun they describe.

Courent is the third person plural form of courir (to run) in the present tense, because the subject is les enfants (the children), which is plural.

Conjugation:

• je cours
• tu cours
• il/elle court
• nous courons
• vous courez
• ils/elles courent

So:

• les enfants courent = the children run / are running

It can mean either, depending on context. The French present tense often covers both the English simple present and present progressive.

So les enfants courent could mean:

• the children run
• the children are running

In this sentence, English would probably most naturally say the children run if it is a general scene, or the children are running if describing a specific moment. French uses the same form for both.

Entre usually means between or among, depending on context.

Here:

• entre les dunes = between the dunes / among the dunes

Because dunes is plural, English may choose either translation:

• between the dunes if you imagine spaces separating them
• among the dunes if you imagine movement through a dune area

Both capture the French well.

Les is the plural definite article, meaning the.

So:

• la dune = the dune
• les dunes = the dunes

French marks plural clearly with the article, even though the final -s is often silent in pronunciation.

This is a very common learner question.

In French, possessive adjectives agree with the thing possessed, not with the possessor.

So:

• leur seau = their bucket / their bucket each / their bucket collectively
• leurs seaux = their buckets

Because seau is singular here, French uses leur.

Even though les enfants is plural, leur is still correct if each child is associated with one bucket, or if the sentence treats the bucket as a shared item in a general way.

Because the owners are plural: les enfants.

French possessives work like this:

• son / sa / ses = his / her / its
• leur / leurs = their

So:

• avec son seau = with his/her bucket
• avec leur seau = with their bucket
• avec leurs seaux = with their buckets

Again, the choice between leur and leurs depends on whether the possessed noun is singular or plural.

Seau means bucket, and it is pronounced like so.

Its spelling is unusual for English speakers, because eau in French often sounds like o:

• seau
• eau
• beau

So even though it has several letters, the pronunciation is simple: one vowel sound.

The plural is seaux, but it is pronounced the same way:

• seau = singular
• seaux = plural

The word order is very normal French word order.

Structure:

• Quand la marée est basse = time clause
• les enfants courent = subject + verb
• entre les dunes = place
• avec leur seau = accompaniment / what they have with them

So the sentence is built very naturally:

1. time/background
2. main subject and action
3. place
4. additional detail

English often does something very similar:

• When the tide is low, the children run between the dunes with their bucket.

The comma is used because the sentence begins with a subordinate clause:

• Quand la marée est basse, ...

This is similar to English, where a comma is also commonly used after an introductory when clause.

It helps separate:

• the introductory time clause
• the main clause

So it is both natural and standard here.