Du kan låna vilken bok som helst här.

Du is the normal singular word for you in Swedish. It is what you use when speaking to one person in most everyday situations.

Swedish also has ni, but:

• ni is mainly plural = you all / you guys / you both
• in some situations it can be used politely to one person, but that is much less central than English polite you

So Du kan låna vilken bok som helst här is simply addressing one person directly.

Kan is the present tense of kunna, and it usually means can.

In a sentence like this, it often expresses:

• ability
• possibility
• practical availability

So here it suggests something like:

• it is possible for you to borrow any book here
• you are able to borrow any book here

Depending on context, it may also feel close to you may borrow.

Because kan is a modal verb, and modal verbs in Swedish are normally followed directly by the infinitive.

So:

• Du kan låna
• not Du kan att låna

This is similar to English:

• You can borrow
• not You can to borrow

Other common Swedish modal verbs work the same way, such as ska, vill, måste, and får.

For learners, the safest rule is:

• låna = borrow
• låna ut = lend

So in this sentence, låna clearly means borrow.

Examples:

• Jag lånar en bok = I am borrowing a book
• Jag lånar ut en bok = I am lending out a book

You may sometimes hear broader colloquial uses, but at beginner level, this rule will keep you out of trouble.

This is a very common Swedish way to say any book at all or whichever book you want.

It is built like this:

• vilken = which
• bok = book
• som helst = roughly ever / at all / whatsoever in this kind of structure

So the whole phrase means that there is no special restriction: you may choose freely.

It is stronger and more specific than just saying en bok.

Som helst is an idiomatic expression that turns words like which, who, where, and when into an any- meaning.

Examples:

• vilken som helst = any one at all
• vem som helst = anyone
• var som helst = anywhere
• när som helst = anytime

So in vilken bok som helst, som helst adds the idea of no matter which one.

You should learn it as a fixed pattern rather than trying to translate each word literally every time.

Because bok is a common-gender noun, an en-word:

• en bok

The forms are:

• vilken for en-words
• vilket for ett-words
• vilka for plural

So:

• vilken bok = which book
• vilket hus = which house
• vilka böcker = which books

That is why the sentence has vilken bok som helst.

Because the phrase is talking about any single book you choose.

In Swedish, vilken + singular noun + som helst is the normal pattern when you mean any one X:

• vilken bok som helst = any book
• vilken film som helst = any film

If you wanted a plural idea, you could say:

• vilka böcker som helst = any books

The singular here does not mean only one specific book is allowed. It just means any individual book.

Yes, but it is not exactly the same.

• någon bok can mean some book or any book, depending on context
• vilken bok som helst more clearly means absolutely any book / whichever book

So:

• Du kan låna någon bok här sounds less natural if you mean free choice
• Du kan låna vilken bok som helst här clearly says there is open choice

In other words, vilken bok som helst is stronger and more precise here.

Här means here, and Swedish often places short adverbs of place near the end of the sentence.

So this word order is very natural:

• Du kan låna vilken bok som helst här

It tells us the location of the borrowing.

You can move här for emphasis, but then the sentence must still follow Swedish V2 word order:

• Här kan du låna vilken bok som helst

That version puts more focus on here.

Yes, and that is a useful comparison.

• kan = can, are able to, it is possible
• får = may, are allowed to

So:

• Du kan låna vilken bok som helst här = You can borrow any book here
• Du får låna vilken bok som helst här = You are allowed to borrow any book here

In real life, kan can sometimes imply permission too, depending on context. But får is more clearly about permission.

Yes, it is completely natural.

It would fit well in contexts like:

• a library
• a classroom
• a waiting room
• a book exchange
• a friend’s home

It sounds like someone is telling you that the selection is open and you do not need to ask about each individual book.