Restaffaldet er i beholderen.

Because Danish usually puts the definite article on the end of the noun instead of using a separate word like the.

So:

• restaffald = residual waste / non-recyclable waste
• restaffaldet = the residual waste

The ending -et is the definite ending for many neuter nouns.

Danish nouns have grammatical gender, and that affects the definite ending.

Here:

• en beholder = a container/bin
• beholderen = the container/bin

So beholder is a common gender noun, and common gender nouns usually take -en in the definite singular.

By contrast:

• et restaffald is not how you would normally say it in practice, because restaffald behaves like a mass noun, but grammatically it is based on a neuter noun, so the definite form is restaffaldet.

A useful shortcut is:

• common gender definite singular: -en
• neuter definite singular: -et

In simple noun phrases, Danish normally attaches the to the noun.

So English and Danish line up like this:

• the container → beholderen
• the residual waste → restaffaldet

That is the normal pattern when there is no adjective.

If you add an adjective, Danish usually changes the structure:

• the container → beholderen
• the big container → den store beholder

So with adjectives, Danish often uses a separate article word such as den or det instead of the suffixed article.

It is a compound noun:

• rest = remainder / leftover
• affald = waste / garbage

So restaffald literally means something like remaining waste or leftover waste. In everyday use, it usually means the waste that does not go in the recycling categories.

This is very common in Danish: nouns are often built by joining smaller nouns or word parts together.

Er is the present tense of at være = to be.

So:

• er = is / are / am, depending on context

In this sentence, er i means is in:

• Restaffaldet er i beholderen = The residual waste is in the container.

Danish does not change the verb form for different persons the way English does. The present form er stays the same:

• jeg er = I am
• du er = you are
• det er = it is
• de er = they are

I means in.

So i beholderen means in the container.

This is the normal preposition when something is inside something else. It is very close to English here.

Compare:

• på bordet = on the table
• i kassen = in the box
• i beholderen = in the container

In this sentence, it is very similar to English:

• Restaffaldet = subject
• er = verb
• i beholderen = prepositional phrase

So the order is:

subject + verb + place

However, Danish main clauses follow the verb-second rule. That means the finite verb usually comes second in the sentence, even if something other than the subject comes first.

For example:

• Restaffaldet er i beholderen.
• I beholderen er restaffaldet.

Both are possible, but the second one is more marked and emphasizes the location.

Using restaffaldet makes the noun definite: the residual waste.

Using just restaffald would sound more general, more like talking about the category or substance:

• Restaffald skal i den sorte beholder. = Residual waste goes in the black container.
• Restaffaldet er i beholderen. = The residual waste is in the container.

So the definite form often points to a specific, known thing, while the bare form can sound more general.

It can mean container, receptacle, or bin, depending on context.

In a waste-sorting context, beholderen often refers to the waste bin or collection container. So even if the dictionary gives container, the natural English translation in context might be bin.

That is common in Danish: a word may be slightly broader than the most obvious English equivalent.

The most important thing for an English speaker is this:

• the ending -et in restaffaldet is usually unstressed
• the ending -en in beholderen is also unstressed
• the letter d in Danish is often very soft, especially inside a word or before an ending

So you should not pronounce them like clear English d sounds.

A practical learner-friendly approach is:

• restaffaldet: stress the main part of the word, and make the ending light
• beholderen: stress holder, and again keep the ending light

If your pronunciation is not perfect yet, getting the rhythm right matters more than saying a strong English-style d.

In Danish compounds, the last part usually determines the grammatical gender.

Here the last part is affald, so the compound follows that noun’s gender. That is why the definite form is restaffaldet.

This is a very useful rule for learners:

• look at the final part of the compound
• that part usually controls gender and inflection

For example, if the last part is a noun that takes -et in the definite form, the whole compound usually will too.

Yes, and it means something slightly different in focus.

• Restaffaldet er i beholderen. = The residual waste is in the container.
  This points to a specific known thing.

• Der er restaffald i beholderen. = There is residual waste in the container.
  This presents the existence of some residual waste in the container.

So both are grammatical, but they are used in different situations. The original sentence is more definite and specific.