Am Wochenende macht meine Cousine Müsli mit Erdbeeren und Pfirsichen für alle.

Am Wochenende means at the weekend or on the weekend.

German often puts a time expression first in the sentence. When that happens, the verb still has to stay in the second position, so the sentence becomes:

Am Wochenende macht meine Cousine ...

instead of the more basic order:

Meine Cousine macht am Wochenende ...

Both are correct. Starting with Am Wochenende just emphasizes the time.

Am is a contraction of an dem.

So:

• an dem Wochenende → am Wochenende

This is a common fixed expression in German for talking about weekends.

A learner should mainly remember it as a standard phrase:

• am Wochenende = at/on the weekend

Because the subject is meine Cousine, which is third person singular: she.

The verb machen is conjugated like this in the present tense:

• ich mache
• du machst
• er/sie/es macht
• wir machen
• ihr macht
• sie/Sie machen

So with meine Cousine, you need macht.

This is because German is a verb-second language.

In a normal main clause, the finite verb must be in the second position. If you put something else first, like a time phrase, the subject usually comes after the verb.

So:

• Meine Cousine macht am Wochenende Müsli ...
• Am Wochenende macht meine Cousine Müsli ...

Both are correct.

The important rule is:

• first position: one sentence element
• second position: the conjugated verb

German often leaves out the article with food, drink, and other uncountable or general nouns when speaking in a general sense.

So macht Müsli means makes muesli.

You could say ein Müsli in some contexts, but that would sound more like a bowl/serving/type of muesli, depending on context. Here, the article is naturally omitted.

The preposition mit always takes the dative case.

So the nouns after mit must be in the dative plural:

• die Erdbeeren → mit Erdbeeren
• die Pfirsiche → mit Pfirsichen

That is why you see Pfirsichen.

A useful rule:

• mit
  • dative

Both nouns are plural, but they behave slightly differently in the dative plural.

Erdbeeren

The plural is already Erdbeeren, and it already ends in -n.
So in the dative plural, it stays:

• die Erdbeeren
• mit Erdbeeren

Pfirsiche

The plural is Pfirsiche.
In the dative plural, many German nouns add -n if possible:

• die Pfirsiche
• mit Pfirsichen

So the rule is:

• dative plural usually adds -n
• but if the plural already ends in -n or -s, nothing extra is added

Because für always takes the accusative case, and alle here is the correct accusative form.

So:

• für alle = for everyone / for all

Compare:

• für mich
• für dich
• für uns
• für alle

A helpful rule:

• für
  • accusative

It can mean either, depending on context, but in this sentence it most naturally means everyone or all the people involved.

So für alle means:

• for everyone
• for everybody
• possibly for all of them, if the people are already known from context

German often uses alle in this broad way without needing a noun after it.

Because in German, all nouns are capitalized.

So:

• das Wochenende
• die Cousine
• das Müsli
• die Erdbeeren
• die Pfirsiche

This is one of the most noticeable spelling differences from English.

Yes. German word order is flexible, as long as the verb-second rule is respected in main clauses.

For example, these are also possible:

• Meine Cousine macht am Wochenende Müsli mit Erdbeeren und Pfirsichen für alle.
• Für alle macht meine Cousine am Wochenende Müsli mit Erdbeeren und Pfirsichen.

These versions shift the emphasis:

• Am Wochenende ... emphasizes when
• Meine Cousine ... emphasizes who
• Für alle ... emphasizes for whom

Here it means makes.

The verb machen can mean do or make depending on context. In this sentence:

• Müsli machen = to make muesli

So macht is best translated as makes.

A useful breakdown is:

• Am Wochenende = time expression
• macht = conjugated verb
• meine Cousine = subject
• Müsli = direct object / thing being made
• mit Erdbeeren und Pfirsichen = prepositional phrase describing what is in it
• für alle = prepositional phrase meaning who it is for

So the pattern is roughly:

Time + Verb + Subject + Object + Extra information

That is a very common German sentence structure.