Meine Schwester will die Kuchenform erst aus dem Schrank rausnehmen, wenn der Teig fertig ist.

In German, wollen means to want. So Meine Schwester will ... rausnehmen means My sister wants to take out ...

This is a very common false friend for English speakers, because English will often marks the future, but German will usually expresses desire or intention.

• Ich will gehen. = I want to go.
• Future in German is often just the present tense, or sometimes werden:
  • Ich gehe morgen. = I’m going tomorrow.
  • Ich werde morgen gehen. = I will go tomorrow.

So here, will is from wollen, not a future marker.

Because the sentence uses the modal verb will. In German, when you have a modal verb such as wollen, können, müssen, dürfen, sollen, or mögen, the main verb goes to the end in the infinitive.

So:

• Meine Schwester will ... rausnehmen.

Here:

• will = the conjugated modal verb in second position
• rausnehmen = the infinitive at the end

Also, rausnehmen is a separable verb, but when it appears as an infinitive with a modal, it stays together as rausnehmen.

Compare:

• Sie nimmt die Kuchenform raus.
• Sie will die Kuchenform rausnehmen.

Rausnehmen is a separable verb. It is built from:

• raus = out
• nehmen = to take

In many forms, the prefix separates:

• Ich nehme die Form raus.
• Sie nimmt die Kuchenform raus.

But in the infinitive, and after a modal verb, it stays together:

• die Kuchenform rausnehmen
• Sie will die Kuchenform rausnehmen.

A more standard or less colloquial version is herausnehmen.
So rausnehmen and herausnehmen are very close in meaning, but rausnehmen sounds more everyday and spoken.

Here erst means something like not until or only then.

So:

• ... erst rausnehmen, wenn der Teig fertig ist
  means
• ... only take it out when the batter/dough is ready
• or more naturally in English: ... not take it out until the batter/dough is ready

This is a very common use of erst. It does not mean first here.

Compare:

• Ich esse erst später. = I’m only eating later / not until later.
• Wir gehen erst morgen. = We’re not going until tomorrow.

So in this sentence, erst adds the idea of waiting until the right moment.

Wenn is used because the sentence describes a condition or a repeated/general situation: when the batter is ready.

German learners often compare wenn, als, and wann:

• wenn = when / if, for conditions or repeated/general situations
• als = when, for a single event in the past
• wann = when?, in direct or indirect questions

Here, the sentence is not asking when?, so wann is impossible.

And it is not referring to one completed past event, so als is not used.

So:

• ..., wenn der Teig fertig ist. = ..., when the batter is ready.

Because wenn introduces a subordinate clause, and in German subordinate clauses the conjugated verb normally goes to the end.

So:

• wenn der Teig fertig ist

Breakdown:

• wenn = subordinating conjunction
• der Teig = subject
• fertig = predicate adjective
• ist = conjugated verb, placed at the end

This is one of the most important German word-order rules.

Compare:

• Main clause: Der Teig ist fertig.
• Subordinate clause: ..., wenn der Teig fertig ist.

Because the two nouns have different grammatical roles and cases.

die Kuchenform is the direct object of rausnehmen, so it is in the accusative.

• die Kuchenform = accusative feminine
• Feminine article in accusative is still die

dem Schrank comes after the preposition aus, and aus always takes the dative.

• aus dem Schrank = out of the cupboard/cabinet
• der Schrank becomes dem Schrank in the dative masculine

So:

• die Kuchenform = thing being taken out
• aus dem Schrank = place it is being taken from

The preposition aus always takes the dative case. It usually means out of, from inside, or from.

Examples:

• aus dem Haus = out of the house
• aus der Tasche = out of the bag
• aus dem Schrank = out of the cupboard

So you simply have to learn aus + dative as a fixed rule.

In this sentence:

• nominative: der Schrank
• dative after aus: dem Schrank

Kuchenform means a cake pan, cake tin, or cake mold, depending on context and region.

It is made up of:

• Kuchen = cake
• Form = mold/pan/tin/shape

So literally it is a cake form.

A native English speaker might expect something more like cake pan, but German often creates compound nouns like this.

It can mean either, depending on context.

German Teig is broader than English dough. It can refer to:

• bread dough
• pastry dough
• cake batter

Since the sentence mentions a Kuchenform, many learners would naturally understand Teig here as cake batter or possibly cake mixture.

So if the English translation you saw says batter, that makes sense in this context.

Yes. Rausnehmen and herausnehmen mean basically the same thing.

• rausnehmen = more everyday, conversational
• herausnehmen = slightly more formal or neutral

So these are both possible:

• Meine Schwester will die Kuchenform erst aus dem Schrank rausnehmen, wenn der Teig fertig ist.
• Meine Schwester will die Kuchenform erst aus dem Schrank herausnehmen, wenn der Teig fertig ist.

In spoken German, rausnehmen is very common.

Yes, both contribute to the idea of out, and German often allows this kind of doubling.

• aus dem Schrank = out of the cupboard
• rausnehmen = take out

Together they sound natural in German:

• die Kuchenform aus dem Schrank rausnehmen

English often avoids this kind of doubling more than German does, but German speakers commonly use both the prepositional phrase and the separable prefix.

You could think of it as:

• take the cake pan out of the cupboard

English also has both take out and out of the cupboard, so it is not actually that strange.

Yes, some parts can move around, although the original sentence is very natural.

German word order is flexible, but not random. The fixed points here are:

• will must be in second position in the main clause
• rausnehmen goes to the end because of the modal
• ist goes to the end of the wenn clause

The middle part can shift somewhat for emphasis. For example, you could also hear:

• Meine Schwester will erst die Kuchenform aus dem Schrank rausnehmen, wenn der Teig fertig ist.

This slightly changes the focus of erst. In the original sentence, erst is closely tied to the action rausnehmen: she wants to take it out only at that point.

So yes, some movement is possible, but the given sentence is idiomatic and well-formed.

The main clause is:

• Meine Schwester will die Kuchenform erst aus dem Schrank rausnehmen

The subordinate clause is:

• wenn der Teig fertig ist

A useful way to see it is:

• Subject: Meine Schwester
• Finite verb: will
• Object: die Kuchenform
• Time/limiting word: erst
• Prepositional phrase: aus dem Schrank
• Infinitive: rausnehmen
• Subordinate clause: wenn der Teig fertig ist

So the overall pattern is:

[Main clause] + [subordinate clause introduced by wenn]

That is a very common German sentence pattern.