Berendezzük a szobát, és a dekoráció is kész.

Because the verb has a definite object: a szobát = the room.

Hungarian has two main present-tense conjugations:

• indefinite conjugation, used when there is no definite object
• definite conjugation, used when the object is definite

Here, a szobát is definite, so the verb takes the definite we ending:

• berendezünk = we furnish / we arrange (something, in general)
• berendezzük = we furnish / we arrange it / the room

So berendezzük a szobát is the natural form.

Because it is the direct object of the verb, so it takes the accusative ending -t.

• a szoba = the room
• a szobát = the room (as the thing being furnished/arranged)

This is very common in Hungarian:

• olvasom a könyvet = I read the book
• látjuk a házat = we see the house

So in this sentence, a szobát shows what is being furnished.

Berendez means something like:

• to furnish
• to arrange
• to set up
• to fit out

When used with a room, it often means to furnish a room or to arrange it so it is ready to use/live in.

The prefix be- often gives a sense of inward or completing/putting into place, so berendezni egy szobát is more than just moving one object around; it suggests arranging the room as a whole.

Because Hungarian usually does not need subject pronouns when the verb ending already shows the subject.

Berendezzük already tells you:

• present tense
• first person plural
• we

So mi = we is normally left out unless you want extra emphasis:

• Berendezzük a szobát. = We furnish the room.
• Mi rendezzük be a szobát. = We are the ones furnishing the room.

In Hungarian, the verb van = to be is usually omitted in the present tense, third person singular/plural when the predicate is a noun, adjective, or similar expression.

So:

• A dekoráció kész. = The decoration is ready.
• literally, there is no spoken is

But in other persons or tenses, van appears:

• Kész vagyok. = I am ready.
• A dekoráció kész volt. = The decoration was ready.
• A dekoráció kész lesz. = The decoration will be ready.

So a dekoráció is kész is perfectly normal Hungarian.

Here is means also or too.

So:

• a dekoráció is kész = the decoration is ready too / also

Hungarian is usually comes right after the word it refers to.

Here it follows a dekoráció, so the meaning is:

• the decoration too is ready

Compare:

• A dekoráció is kész. = The decoration is ready too.
• A dekoráció kész is. = less neutral; this would shift the emphasis and is not the normal wording here.

Because Hungarian places is directly after the element it modifies.

English often puts too at the end:

• The decoration is ready too.

Hungarian usually does this instead:

• A dekoráció is kész.

That tells you that the decoration is the extra item being added to the situation.

This is a very important Hungarian pattern:

• Péter is jön. = Péter is coming too.
• Én is tudom. = I know too.
• Holnap is dolgozunk. = We are working tomorrow too.

Kész can mean both ready and finished/completed, depending on context.

In this sentence, a dekoráció is kész most naturally means:

• the decoration is ready or
• the decoration is finished too

Both ideas are close. It suggests the decoration work has been completed and is now ready.

This is common with kész:

• Kész a vacsora. = Dinner is ready.
• Kész a feladat. = The task is finished.
• Kész vagyok. = I am ready / I’m done.

Berendezzük a szobát is the more neutral word order: verb + object.

Hungarian word order is flexible, but it is often used to show focus or emphasis.

• Berendezzük a szobát. = neutral, matter-of-fact
• A szobát berendezzük. = puts more emphasis on the room; it may sound like As for the room, we’ll furnish it or It’s the room that we’ll furnish

So the version in your sentence is the plain, natural one.

Because és joins two full clauses here:

• Berendezzük a szobát
• a dekoráció is kész

Each part could stand on its own as a sentence, so the comma is normal in Hungarian punctuation.

This is similar to English:

• We furnish the room, and the decoration is ready too.

Formally, it is present tense. But in Hungarian, the present tense can often be used for a planned future action, especially when the context makes that clear.

So depending on context, Berendezzük a szobát can mean:

• We furnish the room
• We are furnishing the room
• We’ll furnish the room

Hungarian does this quite naturally. If the meaning shown to you is future-like, that is not strange at all.

Yes, dekoráció is a normal Hungarian word, borrowed from an international source, and it means decoration.

It sounds fairly standard and natural, especially in contexts like:

• interior decoration
• event decoration
• festive decoration

Depending on context, Hungarians might also use other words such as:

• díszítés = decoration, decorating
• dísz = ornament / decorative item

But a dekoráció is kész is completely normal.

Because both nouns are definite:

• a szobát = the room
• a dekoráció = the decoration

Hungarian uses a / az as the definite article, like English the.

Which form appears depends on the next sound:

• a before a consonant: a szoba
• az before a vowel: az asztal

In your sentence, both nouns begin with consonants, so both take a.