Tom snijdt het brood, terwijl Anna de appels schilt.

Because terwijl introduces a subordinate clause.

In Dutch:

• a main clause usually has the finite verb in second position
• a subordinate clause usually sends the finite verb to the end

So:

• Tom snijdt het brood = main clause
• terwijl Anna de appels schilt = subordinate clause

That is why you get Anna de appels schilt, not Anna schilt de appels after terwijl.

Here terwijl means while, showing that two actions are happening at the same time.

So the sentence describes:

• Tom is cutting the bread
• at the same time, Anna is peeling the apples

In other contexts, terwijl can also sometimes suggest contrast, a bit like whereas, but in this sentence it is simply about simultaneous actions.

They are both present-tense forms with a third-person singular subject:

• Tom snijdt
• Anna schilt

Dutch present tense often works like this:

• ik snijd
• jij snijdt
• hij/zij snijdt

And:

• ik schil
• jij schilt
• hij/zij schilt

So the -t is the normal ending for he/she/it and usually jij/u as well.

The infinitives are:

• snijden = to cut
• schillen = to peel

So:

• snijdt comes from snijden
• schilt comes from schillen

This is useful because Dutch dictionaries list verbs under the infinitive form.

Dutch nouns take either de or het as their definite article.

• brood is a het-word, so: het brood
• appel is a de-word, so the singular is: de appel

But there is an important rule:

• all plural nouns take de

So:

• singular: de appel
• plural: de appels

That is why the sentence has:

• het brood
• de appels

Because brood is often treated as an uncountable mass noun, like bread in English.

So Dutch commonly says:

• het brood snijden = to cut the bread

But appels are countable individual items, so the plural is natural:

• de appels schillen = to peel the apples

If you wanted to talk about individual loaves, you would use a countable noun such as broden or more naturally broden/een brood/een loaf-type expression, depending on context. But in everyday Dutch, brood often behaves just like English bread.

Because Dutch often uses the simple present where English uses the present continuous.

So:

• Tom snijdt het brood can mean
• Tom cuts the bread or, more naturally in this context,
• Tom is cutting the bread

And:

• Anna schilt de appels can mean
• Anna peels the apples or
• Anna is peeling the apples

Dutch does have ways to stress ongoing action, such as aan het + infinitive, but it is not necessary here.

Yes. That is completely correct.

When the terwijl clause comes first, the main clause still follows the Dutch verb-second rule. So after the opening subordinate clause, the finite verb of the main clause comes immediately:

• Terwijl Anna de appels schilt, snijdt Tom het brood.

Notice that you do not say:

• Terwijl Anna de appels schilt, Tom snijdt het brood.

That would be wrong, because the main clause verb must come before the subject there.

Yes, in normal written Dutch the comma is standard here.

You usually separate a subordinate clause introduced by words like terwijl, omdat, als, wanneer, and dat with a comma, especially when the clause comes after the main clause or before it.

So these are standard:

• Tom snijdt het brood, terwijl Anna de appels schilt.
• Terwijl Anna de appels schilt, snijdt Tom het brood.

In speech, the pause may be small, but in writing the comma is expected.

For many learners, snijdt looks harder than it sounds.

A few helpful points:

• snijdt comes from snijden
• the ij sounds roughly like the vowel in English eye, though not exactly the same
• the written dt at the end does not mean you pronounce a strong separate d and t

So snijdt is pronounced roughly like snijt.

Also:

• schilt begins with the Dutch sch sound, which is more guttural than English sh
• appels has a simple plural ending: appel → appels

The spelling is tied to grammar, so Dutch sometimes writes more letters than you clearly hear.

Because the sentence is talking about specific apples, not apples in general.

• de appels = the apples
• appels by itself would sound more general or less anchored in a specific situation

Since this sentence paints a concrete scene with Tom and Anna doing particular actions, the definite article is natural:

• Tom is cutting the bread
• Anna is peeling the apples

Dutch often uses articles in places where English learners may be tempted to leave them out.

Usually not in this sentence if you want the meaning while in the sense of two simultaneous actions.

• terwijl = while
• als / wanneer = when

So:

• Tom snijdt het brood, terwijl Anna de appels schilt = both things are happening at the same time

If you used als or wanneer, it would sound more like when Anna peels the apples, which changes the relationship between the two actions.

For straightforward simultaneity, terwijl is the best choice here.