De regenton staat naast de composthoop.

Because both regenton and composthoop are de-words in Dutch.

Dutch singular definite articles are:

• de for common-gender nouns
• het for neuter nouns

So:

• de regenton
• de composthoop

In the plural, almost all nouns take de, so you would also get:

• de regentonnen
• de composthopen

Dutch often uses a position verb where English would simply use is.

Here, staan literally means to stand, but in many location sentences it means something like to be standing / to be located. Dutch commonly uses:

• staan for things seen as upright or standing
• liggen for things lying down
• zitten for things located in, on, or attached to something in a more fixed way

A rain barrel is thought of as an upright object, so De regenton staat ... sounds natural.

English says The rain barrel is next to the compost heap, but Dutch prefers staat here.

Dutch is a V2 language, which means the finite verb normally comes in the second main slot of a main clause.

So in:

• De regenton staat naast de composthoop.

the structure is:

• De regenton = first element
• staat = finite verb in second position
• naast de composthoop = rest of the sentence

You can move another element to the front, but the verb still stays second:

• Naast de composthoop staat de regenton.

That also means The rain barrel is next to the compost heap, but with more focus on the location.

Because Dutch usually writes compound nouns as one word.

So:

• compost
  • hoop = composthoop
• regen
  • ton = regenton

This is very normal in Dutch. English often uses separate words where Dutch uses one compound.

A useful rule: in Dutch compounds, the last part is the main noun. That last part determines things like:

• the article
• the plural pattern
• the general core meaning

So composthoop is a kind of hoop, and regenton is a kind of ton.

Because naast by itself is already a complete preposition meaning next to / beside.

So you simply say:

• naast de composthoop
• naast het huis
• naast de deur

You do not add another preposition like aan here.

Yes. In many contexts, naast can be translated as either next to or beside.

Examples:

• De fiets staat naast het huis.
• The bike is next to the house.
• The bike is beside the house.

The exact English choice depends on style, but the Dutch word stays the same.

Yes, but the meaning becomes less precise.

• naast de composthoop = specifically next to the compost heap
• bij de composthoop = near / by / at the compost heap

So if you mean the rain barrel is directly beside it, naast is better.
If you just mean it is somewhere in that area, bij could work.

You would make both the subject and the verb plural:

• De regentonnen staan naast de composthopen.

Changes:

• regenton → regentonnen
• staat → staan
• composthoop → composthopen

If only the rain barrels are plural, then:

• De regentonnen staan naast de composthoop.

Dutch plural formation is not completely regular, so you often have to learn the plural with the noun.

Here:

• hoop → hopen
• ton → tonnen

A few things are happening:

• Many Dutch nouns take -en in the plural.
• Some words also double the consonant to keep the vowel pronunciation short, as in ton → tonnen.

This is why compounds behave like:

• regenton → regentonnen
• composthoop → composthopen

Again, the plural behavior is mainly determined by the last part of the compound.

Both views are useful.

It is one noun: regenton.
But it is also clearly built from:

• regen = rain
• ton = barrel / cask

So a regenton is literally a rain barrel.

This is very common in Dutch and can help vocabulary building. If you learn the parts, you can often guess the meaning of compounds.

A rough English approximation is something like staaht, but not exactly.

A few pronunciation notes:

• aa is a long vowel
• final t is clearly pronounced
• the st at the beginning is like English st

So staat sounds straightforward compared with some harder Dutch words.

If pronunciation is your focus, the trickier words in this sentence are often:

• regenton because of the Dutch g
• composthoop because of the long oo

In compounds, Dutch usually stresses the first part more strongly.

So typically:

• REgen-ton
• COMpost-hoop

That first-part stress is very common in Dutch compounds and can help your pronunciation sound more natural.

Yes, absolutely.

That sentence is perfectly grammatical:

• Naast de composthoop staat de regenton.

It means the same basic thing, but the focus shifts slightly to the location. This is a very common Dutch pattern: move an element to the front for emphasis, and keep the verb in second position.

So compare:

• De regenton staat naast de composthoop. → neutral
• Naast de composthoop staat de regenton. → emphasizes where it is