Hun vil helst rydde op med det samme, så hun kan slappe af senere på aftenen.

helst means something like preferably, most willingly, or would rather when no direct comparison is stated.

In this sentence, Hun vil helst rydde op ... means she prefers that option.

Use hellere when you are comparing two alternatives:

• Hun vil hellere rydde op nu end i morgen. = She would rather tidy up now than tomorrow.

So:

• helst = general preference
• hellere = preference between two compared options

Here, vil is closer to wants to or would prefer to, especially because it is combined with helst.

So Hun vil helst rydde op ... is not just a neutral future statement. It expresses her preference or wish.

That is why English often translates this more naturally as:

• She would rather tidy up right away or
• She prefers to tidy up right away

Because vil and kan are modal verbs, and after modal verbs Danish uses the bare infinitive.

So you get:

• vil rydde
• kan slappe

not:

• vil at rydde
• kan at slappe

This is similar to English:

• she wants to tidy up but
• she can relax not she can to relax

A few common Danish modal verbs are:

• kan
• vil
• skal
• må
• bør

After these, you normally do not use at.

Yes, rydde op is a fixed verb expression meaning to tidy up.

It is a verb + particle combination, and in Danish these are often written as two words:

• rydde op
• slappe af
• gå ud

So op is part of the meaning, not just an extra word.

You can see the same pattern in other forms:

• Hun rydder op.
• Hun har ryddet op.
• Hun vil rydde op.

So learners should treat rydde op as a single vocabulary item, even though it is written as two words.

med det samme is an idiomatic expression meaning:

• immediately
• right away
• at once

You should learn it as a fixed phrase, because the literal word-for-word meaning is not very helpful.

It is very common in everyday Danish.

A close synonym is straks:

• Hun vil helst rydde op straks.

Both work, but med det samme often sounds very natural and conversational.

Yes. Here så means so or so that.

The idea is:

• she wants to tidy up now
• so that she can relax later

So så hun kan slappe af ... introduces the purpose/result.

A very natural alternative is:

• Hun vil helst rydde op med det samme for at kunne slappe af senere på aftenen.

The difference is mainly structural:

• så hun kan ... = full clause with subject + verb
• for at kunne ... = infinitive construction, no repeated subject

Both are correct. The version with så hun kan often sounds a bit more conversational and explicit.

Usually no. slappe af is the normal expression meaning to relax.

The particle af is part of the verb:

• Hun slapper af.
• Hun kan slappe af.
• Hun har slappet af.

If you remove af, it will usually sound wrong or incomplete in this meaning.

So just like rydde op, slappe af should be learned as a full expression.

Both can be possible, but they are slightly different in feel.

• senere på aftenen = later in the evening
• senere i aften = later tonight

The version with på aftenen focuses on a later point within the evening. It can sound a little more descriptive or slightly more written.

The version with i aften is often more everyday and direct.

Also compare:

• om aftenen = in the evenings / in the evening as a habitual idea

So:

• senere på aftenen = one specific evening, later in that evening
• om aftenen = usually evenings in general

Because Danish main clauses usually follow the V2 rule: the finite verb comes in the second position.

Here the structure is:

• Hun = first element
• vil = finite verb in second position
• helst = adverb
• rydde op = infinitive phrase

So Hun vil helst ... is the normal order.

Hun helst vil ... would be the kind of order you can get inside a subordinate clause:

• Jeg ved, at hun helst vil rydde op med det samme.

That difference is very important in Danish:

• main clause: Hun vil helst ...
• subordinate clause: ... at hun helst vil ...

Yes, it is very normal here.

Danish generally uses commas to separate clauses more clearly than English often does. The comma marks the boundary between:

• Hun vil helst rydde op med det samme and
• så hun kan slappe af senere på aftenen

So even if English learners may be tempted to leave it out, the comma is natural and expected in standard Danish writing.