Au marché, j’achète des pommes de terre et des champignons pour faire un repas simple ce soir.

Because au is the required contraction of à + le.

• à + le = au
• à + les = aux

Since marché is a singular masculine noun, French uses au marché.

Examples:

• au marché
• au restaurant
• aux magasins

In this sentence, Au marché means at the market. French often puts this kind of place phrase at the beginning to set the scene.

French shortens je to j’ before a vowel sound or a silent h.

So:

• je + achète becomes j’achète
• je aime becomes j’aime
• je habite becomes j’habite

This is very common in French and makes pronunciation smoother.

J’achète is in the present tense.

Depending on context, the French present can mean:

• I buy
• I am buying

So this sentence could sound like either a general present or something happening now. French often uses the same present form for both ideas.

If you want to stress right now, French can say:

• Je suis en train d’acheter...

But in everyday French, the simple present is usually enough.

The verb is acheter, but in some present-tense forms the spelling changes to show pronunciation:

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

But:

• nous achetons
• vous achetez

The è shows an open vowel sound. This kind of stem change happens with some French verbs, especially ones like acheter, lever, and similar patterns.

Des is the plural indefinite article. It often corresponds to some in English, though English often leaves it untranslated.

So:

• des pommes de terre = some potatoes
• des champignons = some mushrooms

French usually needs an article where English may not.

Compare:

• I buy potatoes
• J’achète des pommes de terre

It is just the normal French expression for potatoes.

Literally, pomme de terre means apple of the earth or earth apple, but you should learn it as one whole expression meaning potato.

Forms:

• une pomme de terre = a potato
• des pommes de terre = potatoes

You may also hear patates, but that is more informal.

After pour to express purpose, French normally uses the infinitive when the subject stays the same.

So:

• pour faire un repas simple = to make a simple meal
• more literally, in order to make a simple meal

That is why it is faire, not fais or fait.

A useful comparison:

• J’achète des ingrédients pour cuisiner.
• J’achète des ingrédients pour que tu cuisines.

The first uses the infinitive because the same person is doing both actions.
The second changes subject, so it uses pour que plus a conjugated verb.

In French, adjectives often come after the noun, and simple commonly does in this meaning.

So:

• un repas simple = a simple meal

You can say un simple repas, but that often changes the nuance. It can mean something more like:

• just a meal
• merely a meal

So in this sentence, un repas simple is the natural choice because it describes the kind of meal.

French often puts time expressions like ce soir near the end of the sentence, especially when they add final detail.

So this sounds very natural:

• ...pour faire un repas simple ce soir

But French word order is flexible, and you could also say:

• Ce soir, j’achète...
• J’achète ce soir des pommes de terre...

The original version sounds smooth and natural because ce soir neatly finishes the idea.

Also, ce soir means tonight or this evening, not this night.

In this sentence, it means at the market because it sets the location of the action.

French à can sometimes mean to, at, or in, depending on context. Here, the comma and sentence structure show that Au marché is a location phrase:

• Au marché, j’achète... = At the market, I buy...

If you wanted to emphasize movement toward the market, the context would be different, such as:

• Je vais au marché. = I’m going to the market.

The comma shows that Au marché has been moved to the front as a scene-setting phrase.

The sentence could also be written as:

• J’achète des pommes de terre et des champignons au marché pour faire un repas simple ce soir.

That version is also correct. Putting Au marché first gives it a little more emphasis, like setting the scene before the main action.

A rough English-friendly guide is shahm-pee-nyon, but the real French sound is a bit different.

Key parts:

• ch sounds like sh
• gn sounds like ny, similar to the middle of canyon
• the final s is silent
• the last on is nasal

So champignons is approximately shahm-pee-nyon.

A few other useful pronunciation notes from the sentence:

• marché sounds roughly like mar-shay
• j’achète sounds roughly like zhah-shet

These are only approximations, but they help at the beginning.