Im oberen Stockwerk ist jetzt ein neues Büro.

Im is a contraction of in dem.

• in = in
• dem = the (dative singular)

So:

• im oberen Stockwerk = in the upper floor / on the upper floor

German often contracts certain preposition + article combinations:

• in dem → im
• an dem → am
• zu dem → zum
• bei dem → beim

Because oberen is the correct adjective ending after dem in the dative singular.

In im oberen Stockwerk:

• im = in dem
• dem is dative singular
• Stockwerk is a neuter noun
• so the adjective ober- takes the ending -en

That gives:

• dem oberen Stockwerk

This is a very common pattern:

• in dem alten Haus
• auf dem kleinen Tisch
• im neuen Büro

Because in can take either the accusative or the dative, depending on meaning.

• dative = location, where something is
• accusative = direction, where something is going

Here, the sentence describes a location:

• Im oberen Stockwerk ist jetzt ein neues Büro.
• The office is there; nothing is moving.

So German uses the dative:

• im oberen Stockwerk

Compare:

• Das Büro ist im oberen Stockwerk. = The office is on the upper floor.
• Wir gehen in das obere Stockwerk. = We are going to the upper floor.

Because German main clauses usually follow the verb-second rule.

That means the finite verb must come in the second position. If you begin the sentence with something other than the subject, the verb still stays second, and the subject comes later.

Here the first element is:

• Im oberen Stockwerk

So the verb must come next:

• Im oberen Stockwerk ist ...

Then the subject comes after that:

• ... ein neues Büro

This is completely normal in German.

A more basic word order would be:

• Ein neues Büro ist jetzt im oberen Stockwerk.

But German often starts with the location for emphasis or natural flow.

The subject is ein neues Büro.

You can tell because it is in the nominative and it agrees with the verb ist.

So the sentence structure is roughly:

• Im oberen Stockwerk = location
• ist = verb
• jetzt = now
• ein neues Büro = subject

Even though the subject comes later than in English, it is still the subject.

Because Büro is a neuter noun, and after ein in the nominative singular, the adjective takes -es.

Breakdown:

• ein = a
• neu- = new
• Büro = office

Since Büro is neuter, you get:

• ein neues Büro

Compare:

• ein neues Büro = a new office
• ein neuer Tisch = a new table
• eine neue Wohnung = a new apartment

You usually learn the gender together with the noun:

• das Büro

Since it is das Büro, it is neuter.

That affects articles and adjective endings:

• das neue Büro
• ein neues Büro
• im neuen Büro

Unfortunately, noun gender in German often has to be memorized, though some endings and patterns can help.

Stockwerk means floor or story of a building.

So:

• das obere Stockwerk = the upper floor / upper story

A related word is Stock, which is also used for floor/story in many contexts. Depending on region and style, you may hear both.

Examples:

• im dritten Stock
• im dritten Stockwerk

Both can mean on the third floor.

Jetzt means now, and in German adverbs like this are fairly movable, but some positions sound more natural than others.

Here:

• Im oberen Stockwerk ist jetzt ein neues Büro.

This sounds natural and means something like:

• There is now a new office on the upper floor.

Placing jetzt after the verb often works well in this kind of sentence. It highlights that the situation is different from before.

Other possible word orders are also possible, with slightly different emphasis:

• Jetzt ist im oberen Stockwerk ein neues Büro.
• Ein neues Büro ist jetzt im oberen Stockwerk.

German word order is flexible, but not random. The position often changes what is emphasized.

Yes, that is also possible.

• Im oberen Stockwerk ist jetzt ein neues Büro.
• Im oberen Stockwerk gibt es jetzt ein neues Büro.

Both can be translated naturally as There is now a new office on the upper floor.

A small nuance:

• ist can sound a little more like stating where the office is
• gibt es can sound more like stating that such an office exists there

In many everyday contexts, both are fine.

Because all German nouns are capitalized.

So in this sentence:

• Stockwerk is a noun
• Büro is a noun

That is why they begin with capital letters.

This is one of the most noticeable spelling features of German.

Not always literally. It depends on context.

das obere Stockwerk can mean:

• the upper floor
• the upstairs floor
• sometimes simply upstairs

So if the meaning has already been given to the learner, it is good to know that German may phrase this a bit differently from natural English.

For example, English might often say:

• There is now a new office upstairs.

Even if German says:

• Im oberen Stockwerk ist jetzt ein neues Büro.

Usually im oberen Stockwerk is the normal choice.

With floors inside a building, German commonly uses in:

• im ersten Stock
• im oberen Stockwerk

Using auf here would usually sound unnatural in standard German.

So for a floor of a building, stick with:

• in / im

not:

• auf

Yes. Because ein neues Büro is indefinite, the sentence naturally introduces or mentions the existence of a new office in that location.

So the feeling is closer to:

• There is now a new office on the upper floor.

If you wanted to talk about a specific office already known to the listener, you would more likely use:

• Das neue Büro ist jetzt im oberen Stockwerk.

That means:

• The new office is now on the upper floor.

So ein vs das changes the feel quite a bit.