Au marché, Marie achète du saumon frais et du brocoli pour le dîner.

Because au is the mandatory contraction of à + le.

• à le marché → au marché
• This happens with masculine singular nouns that take le
• Similarly:
  • à + les → aux
  • de + le → du
  • de + les → des

So au marché literally comes from à le marché, but French always contracts it.

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

So:

• Au marché, Marie achète... = At the market, Marie buys...

This is similar to English fronting, as in At the market, Marie buys... The comma helps show that Au marché is extra background information before the main clause.

You could also say:

• Marie achète du saumon frais et du brocoli au marché pour le dîner.

That would also be correct, but it changes the rhythm and focus a little.

Because Au marché is a fronted introductory phrase.

In English, we often do the same thing:

• At the market, Marie buys...

The comma is not always absolutely required in every short French sentence, but it is very common and natural here because the location phrase comes first and is separated from the main statement.

Because after a subject like Marie, you need a conjugated verb, not the infinitive.

• acheter = to buy
• achète = buys / is buying

Here, Marie is third-person singular, so the verb must be conjugated in the present tense:

• j’achète
• tu achètes
• il / elle / on achète
• nous achetons
• vous achetez
• ils / elles achètent

So Marie achète means Marie buys or Marie is buying, depending on context.

This is part of how the verb acheter is spelled when it is conjugated.

In many forms of acheter, the e in the stem changes to è:

• j’achète
• tu achètes
• il/elle achète
• ils/elles achètent

But:

• nous achetons
• vous achetez

This spelling reflects pronunciation. The accent grave in achète helps show that the vowel is more open than in acheter.

Because du is the partitive article here. It is used for an unspecified amount of something, especially food or drink.

• du saumon = some salmon

French usually requires an article where English often uses none. English says salmon, but French often says du saumon when talking about some amount of salmon.

Also, du is the contraction of de + le, but in this sentence it functions as the masculine singular partitive article.

For the same reason: brocoli is being treated as an unspecified quantity of food.

• du brocoli = some broccoli

French commonly uses the partitive article with foods when you mean some rather than a whole countable item.

So:

• du saumon
• du brocoli

both mean an indefinite amount of those foods.

Because the sentence is talking about the foods as substances or ingredients, not about several individual items.

• du saumon = some salmon
• des saumons = some salmon fish / several salmon

Likewise:

• du brocoli = some broccoli
• des brocolis could mean multiple heads or portions of broccoli, depending on context

When buying food for dinner, French often uses the partitive article because the focus is on some amount of food, not separate countable units.

Yes. Brocoli is masculine singular:

• le brocoli
• du brocoli

That is why the sentence uses du and not de la.

Because most French adjectives come after the noun.

So:

• saumon frais = fresh salmon

This is the normal position for many descriptive adjectives, especially ones like color, origin, shape, and many qualities such as freshness.

A few common adjectives often come before the noun, but frais here naturally comes after saumon.

Because frais agrees with saumon, which is masculine singular.

• masculine singular: frais
• feminine singular: fraîche
• masculine plural: frais
• feminine plural: fraîches

Since saumon is masculine singular, the correct form is frais.

Example:

• du poisson frais
• de la viande fraîche

In this sentence, it most naturally describes only saumon.

• du saumon frais et du brocoli

This is usually understood as:

• fresh salmon
• and broccoli

If you wanted to make it clearly apply to both, you would normally repeat or restructure it, for example:

• du saumon et du brocoli frais
• du saumon frais et du brocoli frais

As written, learners should normally read frais as attached to saumon.

Because these are two separate nouns, and each one normally needs its own article.

• du saumon
• du brocoli

French usually repeats the article in coordinated noun phrases more often than English does. English can say salmon and broccoli with no article at all, but French needs the partitive article for each food item here.

Both patterns can exist in French, but they do not always mean exactly the same thing.

• pour le dîner = for dinner / for the dinner meal
• pour dîner can mean something closer to to have for dinner or for dining, depending on context

In this sentence, pour le dîner clearly means the food is intended for the evening meal. It sounds very natural and specific.

It means dinner, the evening meal.

Be careful, because meal words can vary between French-speaking regions. In many places:

• le petit-déjeuner = breakfast
• le déjeuner = lunch
• le dîner = dinner

But in some regions, especially depending on country or local usage, meal names can differ. For standard modern French in many contexts, le dîner is understood as dinner.

It is the present indicative.

So Marie achète can mean:

• Marie buys
• Marie is buying

French present tense often covers both simple present and present progressive ideas that English separates.

Context tells you whether it is habitual or happening now.

In this sentence, it is understood as at the market, because it goes with the action achète.

• Au marché, Marie achète... = At the market, Marie buys...

If you wanted to the market, you would usually need a verb of movement, such as:

• Marie va au marché. = Marie goes to the market.

So au marché itself can appear with movement verbs or location contexts, but here the meaning is clearly location.

Because it expresses the purpose of the purchase, and French commonly puts that kind of information after the objects.

So the structure is roughly:

• place: Au marché
• subject: Marie
• verb: achète
• objects: du saumon frais et du brocoli
• purpose: pour le dîner

This order sounds natural and clear in French. You could move things around, but the original version is very idiomatic.

A careful approximate pronunciation is:

• Oh mar-shay, ma-ree ah-shet du so-mon fray ay du bro-ko-lee poor luh dee-nay.

A few useful notes:

• au sounds like oh
• marché ends with an ay sound
• achète sounds roughly like ah-shet
• frais sounds like fray
• et is usually pronounced like ay
• dîner ends with nay

In normal speech, French flows smoothly, so words are less separated than in English.