Learn Hardcore German: Wir richten gerade ein kleines möbliertes Zimmer für unsere Freundin ein. - We are currently setting up a small furnished room for our friend.

Einrichten is a separable verb: ein·richten. It usually means to furnish, to arrange, or to set up (a room, an apartment, an office, etc.).

In a main clause with normal word order in German, separable verbs split:

The main part (here: richten) goes in the second position.
The separable prefix (here: ein) goes to the very end of the clause.

So:

Wir richten ein Zimmer ein. = We are furnishing a room.

In your sentence:

Wir (subject)
richten (verb, 2nd position)
gerade ein kleines möbliertes Zimmer für unsere Freundin (middle part)
ein (separable prefix at the end)

That’s why ein appears at the end, not glued to richten.

What’s the difference between "gerade" and "jetzt"? Could I say "Wir richten jetzt ..." instead?

Both gerade and jetzt relate to time, but they feel slightly different:

jetzt = now (this moment), quite neutral.
gerade = right now / currently / in the middle of doing it, often emphasizing that the action is happening at this very time or is in progress.

In this sentence:

Wir richten gerade ein ... Zimmer ein.
= We are in the process of furnishing a small furnished room.

You can say:

Wir richten jetzt ein kleines möbliertes Zimmer für unsere Freundin ein.

That’s also correct.
Jetzt emphasizes the time (now rather than before or later).
Gerade emphasizes that it's actively ongoing, similar to English continuous: “We are just now / currently furnishing …”

Why is it "ein kleines möbliertes Zimmer" and not "einen kleinen möblierten Zimmer"?

The choice between ein and einen, kleines and kleinen, depends on gender and case.

Zimmer is a neuter noun in German: das Zimmer.
The preposition für always takes the accusative case.
So we need: neuter, accusative, singular.

The endings for a neuter noun in the accusative are:

ein (article)
kleines (adjective after ein)
möbliertes (another adjective after ein)

So:

ein kleines möbliertes Zimmer = a small furnished room (neuter accusative)

Einen kleinen möblierten Zimmer would be wrong because:

einen and kleinen are masculine accusative endings, but Zimmer is neuter.

Why does "kleines" and "möbliertes" have -es at the end? How are these adjective endings decided?

The adjective endings depend on:

Case (here: accusative)
Gender (here: neuter)
Number (here: singular)
Type of article (here: ein, an ein-word)

We have:

für → accusative
Zimmer → neuter
ein → indefinite article (ein-word)

For neuter accusative with an ein-word:

ein (article)
Adjectives get -es:
- ein kleines Zimmer
- ein möbliertes Zimmer

With two adjectives, each gets the same ending:

ein kleines möbliertes Zimmer

So the -es on kleines and möbliertes shows:
“After ein, this is a neuter accusative noun.”

What exactly does "möbliert" mean? How is it different from just "Zimmer"?

Möbliert means furnished.

ein Zimmer = a room (no information about furniture)
ein möbliertes Zimmer = a room that already has furniture in it (bed, table, wardrobe, etc.)

A möbliertes Zimmer is typically ready to live in; you don’t have to bring your own furniture.

Why is it "für unsere Freundin" and not "für unserer Freundin"?

Again, this is about case.

Für always takes the accusative case.
Freundin is feminine: die Freundin.
Feminine accusative with a possessive (unser-) is:
- unsere Freundin

So:

unsere Freundin = our (female) friend in the accusative.

Unserer Freundin would be dative feminine:

Wir helfen unserer Freundin. = We help our (female) friend.

But after für we need accusative, so it must be unsere Freundin.

Does "Freundin" always mean “girlfriend” (romantic), or can it also mean “(female) friend”?

Freundin can mean either:

(female) friend, or
girlfriend (romantic partner)

It depends on context.

In this sentence:

für unsere Freundin is ambiguous without extra context. It could be:
“for our (female) friend”
or
“for our girlfriend”

If you want to avoid the romantic reading, people often say:

eine gute Freundin (a good [female] friend)
eine Bekannte (a female acquaintance)

For romantic partners, context or additional wording usually clarifies it.

Why is the subject "wir" and not something like "uns"? What’s the difference?

wir = we (subject pronoun, nominative)
uns = us (object pronoun, accusative or dative)

In this sentence:

Wir are doing the action of furnishing, so wir must be the subject.

Structure:

Wir (subject, nominative)
richten ... ein (verb)
ein kleines möbliertes Zimmer (direct object, accusative)
für unsere Freundin (prepositional phrase with für
- accusative)

If you used uns, it would sound like “Us furnish a small furnished room …”, which is grammatically wrong in German, just like in English.

Where can I put "gerade" in the sentence? Is "Wir gerade ein kleines ... einrichten" possible?

Gerade is fairly flexible, but there are natural and unnatural spots.

Natural positions:

Wir richten gerade ein kleines möbliertes Zimmer für unsere Freundin ein.
Wir richten ein kleines möbliertes Zimmer für unsere Freundin gerade ein. (less common, but okay in speech for emphasis)

Unnatural/wrong:

❌ Wir gerade ein kleines möbliertes Zimmer für unsere Freundin einrichten.
Here, richten is missing in 2nd position, and einrichten is not split.

In a main clause, the finite verb must be in 2nd position, and the separable prefix must go to the end:

Wir richten gerade ... ein.

So gerade can move around in the middle part, but it cannot break the rule that richten is 2nd and ein is at the end.

Why isn’t it "Wir sind gerade dabei, ein Zimmer einzurichten" instead? Is there a difference in meaning?

Both are correct, but with different nuances.

Wir richten gerade ein kleines möbliertes Zimmer für unsere Freundin ein.
- Very direct; uses present tense with "gerade" to express an ongoing action.
- Natural, everyday German.
Wir sind gerade dabei, ein kleines möbliertes Zimmer für unsere Freundin einzurichten.
- Literally: “We are just in the process of furnishing ...”
- Slightly more explicit that you are in the middle of the activity.
- Feels a bit longer, sometimes slightly more formal or explanatory.

Meaning-wise, both convey ongoing action, much like the English continuous (“we are furnishing...”). Version 1 is more concise and very common.

Why is "Zimmer" neuter (das Zimmer) and not masculine or feminine? Is there a rule?

Unfortunately, grammatical gender in German is often arbitrary and must be learned word by word.

das Zimmer = neuter
die Küche = feminine
der Flur = masculine

There is no universal rule that says “All room-words are neuter”. You mostly have to memorize each noun with its article:

das Zimmer
ein Zimmer
im Zimmer (in + dem Zimmer)

Knowing that Zimmer is neuter is what leads to the forms:

ein kleines Zimmer
das kleine Zimmer
für ein kleines Zimmer etc.

Could the sentence start with something other than "Wir"? How would that change the word order?

Yes. In German, one element comes before the finite verb in 2nd position. That element doesn’t have to be the subject.

For example:

Gerade richten wir ein kleines möbliertes Zimmer für unsere Freundin ein.
(Here gerade is in the first position; richten must then remain 2nd; wir moves after the verb.)
Für unsere Freundin richten wir gerade ein kleines möbliertes Zimmer ein.
(Emphasis on for our friend.)

Important:
The finite verb (richten) must stay in 2nd position no matter what comes first:

First element (subject, time, place, etc.)
richten
The rest
ein (separable prefix at the end)

Is there any difference between "ein kleines möbliertes Zimmer" and "ein kleines, möbliertes Zimmer" with a comma?

In normal German usage, you don’t put a comma between parallel adjectives like this when they both directly describe a noun:

ein kleines möbliertes Zimmer = a small furnished room

A comma would be unusual here and not standard:

❌ ein kleines, möbliertes Zimmer

You normally use a comma between adjectives only when they are more loosely connected or when it really helps clarity in longer strings. Here, they belong tightly together as a simple list of qualities: small and furnished.