Vi har ett stort bord i vardagsrummet.

Because bord is an ett-word in Swedish, also called a neuter noun. In the singular indefinite form, Swedish nouns take either en or ett:

• en stol = a chair
• ett bord = a table

So you have to say ett bord, not en bord.

A useful habit is to learn Swedish nouns together with their article:

• ett bord
• en bil
• ett hus

The adjective has to agree with the noun.

Since bord is an ett-word, the adjective stor becomes stort in the singular indefinite form:

• en stor stol
• ett stort bord

This is a very common pattern in Swedish:

• en röd bil
• ett rött hus

So ett stort bord is correct because bord is neuter.

Because Swedish usually writes compound nouns as a single word.

So what English writes as living room, Swedish writes as vardagsrum.

This is extremely common in Swedish. For example:

• sjukhus = hospital
• sommarhus = summer house
• matbord = dining table

A native English speaker often wants to separate these words, but in Swedish they are usually written together.

In Swedish, the definite article is usually attached to the end of the noun.

So:

• vardagsrum = living room
• vardagsrummet = the living room

This is different from English, where the comes before the noun. In Swedish, the noun often carries the the meaning as an ending.

Other examples:

• boken = the book
• huset = the house
• bordet = the table

Because vardagsrum is an ett-word, so its definite singular ending is -et.

Pattern:

• ett vardagsrum = a living room
• vardagsrummet = the living room

The same happens with many other neuter nouns:

• ett hus → huset
• ett bord → bordet
• ett rum → rummet

So -et here is the definite ending for an ett-word.

I means in here, and it is the normal preposition for being inside a room or enclosed space.

So:

• i vardagsrummet = in the living room

For rooms, i is the natural choice. A learner might wonder about på, but på vardagsrummet would not be correct here.

Compare:

• i huset = in the house
• i köket = in the kitchen
• i vardagsrummet = in the living room

No, this is the basic Swedish main-clause word order:

subject + verb + object + place

So:

• Vi = subject
• har = verb
• ett stort bord = object
• i vardagsrummet = place

This is very similar to English:

• We have a big table in the living room.

But Swedish also has the important verb-second rule, so if you move the place phrase to the front, the verb still comes second:

• I vardagsrummet har vi ett stort bord.

That is also correct.

Normally, no.

With a singular countable noun in Swedish, you usually need the indefinite article en or ett:

• Vi har ett stort bord.

Without ett, the phrase sounds incomplete or non-standard in ordinary Swedish.

So just as English normally says a big table, Swedish normally says ett stort bord.

Then both the article and the adjective would change.

Compare:

• ett stort bord = a big table
• en stor stol = a big chair

So the pattern is:

• en + stor
• ett + stort

This is one of the most important adjective patterns in Swedish.

A quick comparison:

• en liten bil
• ett litet hus
• en grön stol
• ett grönt bord

Har is the present tense of the verb ha, which means to have.

So:

• ha = to have
• har = have / has

Examples:

• Jag har = I have
• Vi har = we have
• Hon har = she has

In this sentence, Vi har simply means we have.

You usually put inte after the verb in a main clause:

• Vi har inte ett stort bord i vardagsrummet.

That is grammatically possible.

But in natural Swedish, with an indefinite noun, people often prefer:

• Vi har inget stort bord i vardagsrummet.

That means We do not have a big table in the living room.

So inte is the general negation word, but with indefinite nouns you will often also see ingen / inget / inga.