Sæt bogen tilbage på hylden.

Sæt is the imperative form of the verb at sætte (to put / to place / to set).

In Danish, commands usually use the imperative:

• at sætte = to put
• sæt! = put!

So Sæt bogen tilbage på hylden is a command: Put the book back on the shelf.

This is very similar to English using the base verb in commands:

• Put the book back
• Open the door
• Come here

The ending -en makes the noun definite, so bogen means the book, not a book.

Compare:

• en bog = a book
• bogen = the book

Danish often adds the definite article to the end of the noun instead of using a separate word like English the.

For the same reason: hylden means the shelf.

Compare:

• en hylde = a shelf
• hylden = the shelf

So both nouns are definite here:

• bogen = the book
• hylden = the shelf

That matches English Put the book back on the shelf.

Tilbage means back.

It shows that the book is being returned to its earlier place, not just placed somewhere for the first time.

Compare:

• Sæt bogen på hylden = Put the book on the shelf.
• Sæt bogen tilbage på hylden = Put the book back on the shelf.

So tilbage adds the idea of returning something.

Because a book is typically placed on a shelf, and Danish uses på for that.

• på hylden = on the shelf

You would use i when something is inside something:

• i kassen = in the box
• i skuffen = in the drawer

A shelf is treated as a surface/place where something sits, so på is the natural choice.

In Danish commands, the usual order is:

imperative verb + object + adverb

So:

• Sæt bogen tilbage = correct

The version Sæt tilbage bogen sounds unnatural in standard Danish.

A good basic pattern to remember is:

• Tag jakken på = Put on the jacket
• Stil glasset ned = Put the glass down
• Sæt bogen tilbage = Put the book back

So the object usually comes before words like tilbage, ned, op, på, etc.

Sometimes yes, but the choice depends on how the object is being placed.

Very roughly:

• sætte / sæt is often used for putting something into position, especially upright or into a set place
• lægge / læg is often used for laying something down, especially flat

With a book:

• Sæt bogen på hylden often suggests putting it onto the shelf, especially like a normal book placement
• Læg bogen på bordet = Lay the book on the table

For a book on a shelf, sæt is very natural.

Yes. Hylde takes en in the indefinite form:

• en hylde = a shelf

So the definite singular becomes:

• hylden = the shelf

That tells you hylde is a common-gender noun, not a neuter noun.

A learner will often notice that sæt is not pronounced the way it looks to an English speaker.

A few points:

• æ is a front vowel somewhat like the vowel in English cat, but not exactly the same
• the t at the end is pronounced
• the whole word is short and crisp

So sæt is roughly like set said with a more open front vowel, but you should not rely too much on English spelling.

Also, the letter æ is very common in Danish, so it is worth getting used to early.

Because Danish usually attaches the definite article to the end of the noun.

So instead of English:

• the book
• the shelf

Danish usually says:

• bogen
• hylden

This is one of the most important structural differences from English.

However, Danish can also use a separate definite word in some cases, especially with adjectives:

• bogen = the book
• den store bog = the big book

So in your sentence, no separate the is needed.

It is neutral and direct. It sounds like a normal command.

Danish imperatives are commonly used in everyday speech, and they are not automatically rude. Whether they sound polite depends a lot on tone and context.

If you want to sound softer, you could say something like:

• Vil du sætte bogen tilbage på hylden? = Would you put the book back on the shelf?

But the original sentence is completely normal as a straightforward instruction.

Not in this sentence if you keep the same meaning and structure.

The natural order is:

• Sæt bogen tilbage på hylden

Putting tilbage after hylden would sound wrong or very unnatural here.

A useful way to think about it is that tilbage belongs with the action sæt bogen tilbage before the final place phrase på hylden.

So the sentence is built like this:

• Sæt = verb
• bogen = object
• tilbage = back
• på hylden = place

The pattern is:

imperative verb + direct object + adverb + prepositional phrase

In this sentence:

• Sæt = imperative verb
• bogen = direct object
• tilbage = adverb
• på hylden = prepositional phrase showing location

So it is a very useful model for building similar Danish commands:

• Sæt koppen tilbage på bordet
• Læg nøglerne tilbage i skuffen
• Stil flasken tilbage i køleskabet

This makes the sentence a good example of a very common everyday Danish structure.