Na de wandeling nam ik een warm bad.

Na de wandeling is a time expression meaning after the walk. Dutch often puts time information at the beginning of the sentence.

Starting with it gives this structure:

Na de wandeling + nam + ik + een warm bad

This is very natural in Dutch. You could also say:

Ik nam na de wandeling een warm bad.

That version is also correct, but it puts less emphasis on the timing.

Na is a preposition meaning after.

It is followed here by a noun phrase:

na + de wandeling

So this is like saying after the walk.

A useful contrast:

• na de wandeling = after the walk
• nadat ik had gewandeld = after I had walked

So na is used before a noun, while nadat is used before a clause.

Because wandeling is a de-word in Dutch. Nouns in Dutch are learned with their article, so it is best to memorize them together:

• de wandeling
• het bad

There is not always a simple logic you can rely on, so learners usually have to learn the article as part of the vocabulary item.

Nam is the simple past tense of nemen, which means to take.

The verb is irregular:

• infinitive: nemen
• present: ik neem
• past singular: ik nam
• past plural: wij namen
• past participle: genomen

So nam ik means I took.

This is because Dutch main clauses follow the verb-second rule.

That means the finite verb must be in the second position of the sentence. If something other than the subject comes first, the verb still stays second, and the subject moves after it.

So:

• Ik nam een warm bad.
• Na de wandeling nam ik een warm bad.

This inversion is very common in Dutch.

Because bad is a het-word, and with an indefinite singular neuter noun after een, the adjective usually has no -e ending.

So:

• een warm bad ✅
• een warme bad ❌

Compare:

• het warme bad = definite, so the adjective gets -e
• een warme douche = douche is a de-word, so the adjective gets -e

This is an important Dutch adjective rule.

Yes. Een bad nemen is a normal and common way to say to take a bath.

Other possible expressions are:

• in bad gaan = to go take a bath
• baden = to bathe, but this can sound more formal or literary

So in this sentence, een warm bad nemen is perfectly natural Dutch.

Yes, you could.

The difference is:

• na de wandeling = after the walk, a specific walk
• na een wandeling = after a walk, more general or not previously specified

So both are grammatical, but they mean slightly different things.

Usually, no.

In a short sentence like this, Dutch normally does not use a comma after a fronted time phrase:

Na de wandeling nam ik een warm bad.

A comma might appear in longer or heavier sentence openings for readability, but in this sentence, leaving it out is the standard choice.

Because na is used before a noun phrase, and de wandeling is a noun phrase.

• Na de wandeling nam ik een warm bad.
• Nadat ik had gewandeld, nam ik een warm bad.

Both are correct, but the grammar is different:

• na
  • noun
• nadat
  • clause

So the choice depends on what comes next, not just on meaning.