Vi kan spise hvad som helst i aften, så længe der stadig er suppe i fryseren.

It means anything, whatever, or anything at all.

The part som helst adds the idea of no restriction or it does not matter which one. So:

• hvad = what
• hvad som helst = anything / whatever at all

In this sentence, it shows that the speaker has no strong preference about the food choice.

Because noget and hvad som helst do not mean the same thing.

• noget = something
• hvad som helst = anything

So:

• Vi kan spise noget i aften means We can eat something tonight
• Vi kan spise hvad som helst i aften means We can eat anything tonight

The second version sounds much more open-ended.

Here, så længe means as long as or provided that.

So the sentence means that eating anything is acceptable on the condition that there is still soup in the freezer.

Be careful: så længe can also refer to duration in other contexts, like for so long, but not here.

For example:

• Jeg har ventet så længe = I have waited so long
• Så længe der er kaffe, er jeg glad = As long as there is coffee, I am happy

Because så længe introduces a subordinate clause, and Danish word order changes in subordinate clauses.

In a main clause, you would normally say:

• Der er stadig suppe i fryseren

But after a subordinating word like så længe, the usual order is:

• subject + sentence adverb + finite verb

So:

• der = subject
• stadig = adverb
• er = finite verb

That is why you get:

• så længe der stadig er suppe i fryseren

This is a very common Danish pattern.

This der is the same kind of there as in English there is or there are.

So:

• der er suppe = there is soup

It does not mean there as a place.

In other words, der is being used to introduce the existence of something.

Because suppe is being used as an uncountable noun here, like water, milk, or rice.

So:

• der er suppe = there is soup

You do not need an article when you are talking about soup as a substance in general.

If you were talking about a specific soup already known in the conversation, Danish might use the definite form in another structure, such as suppen.

Because:

• i = in
• fryseren = the freezer

Danish usually puts the definite article at the end of the noun:

• en fryser = a freezer
• fryseren = the freezer

So i fryseren literally means in the freezer.

i aften is the normal Danish expression for tonight / this evening.

It is a fixed time expression, so learners should treat it as a chunk.

Compare:

• i aften = tonight
• om aftenen = in the evening / in the evenings
• denne aften = this evening, but this sounds more formal or literary

So for everyday speech, i aften is the natural choice.

Not really physical ability. Here kan is closer to can / may / it is possible to.

So the meaning is more like:

• We can eat anything tonight
• We are free to eat anything tonight
• It is fine for us to eat anything tonight

It is about possibility or acceptability, not about whether the speakers are physically capable of eating.

You could, but it changes the nuance.

• kan = can / are able to / are free to
• må = often may / are allowed to, and sometimes must depending on context

So:

• Vi kan spise hvad som helst i aften sounds neutral: it is possible, acceptable, open
• Vi må spise hvad som helst i aften could sound more like permission, or in some contexts even obligation

In this sentence, kan is the more natural choice.

Sometimes yes, but its position depends on the clause type.

In the main clause version, you would normally say:

• Der er stadig suppe i fryseren

In this sentence, though, the phrase comes after så længe, which creates a subordinate clause, so stadig normally goes before the verb:

• så længe der stadig er suppe i fryseren

So the position of stadig is mainly a word-order issue.

Yes. It is a very common fixed expression, and it is normally written as three words.

There are several similar patterns:

• hvem som helst = anyone
• hvor som helst = anywhere
• hvornår som helst = anytime
• hvilken som helst = any ... whatsoever

So once you learn hvad som helst, you can recognize a whole family of useful expressions.

It breaks down like this:

• Vi = we
• kan spise = can eat
• hvad som helst = anything
• i aften = tonight
• så længe = as long as / provided that
• der stadig er suppe i fryseren = there is still soup in the freezer

So the sentence has:

1. a main clause: Vi kan spise hvad som helst i aften
2. a subordinate condition clause: så længe der stadig er suppe i fryseren

That is a very common and useful sentence pattern in Danish.