Al menjador hi ha una llum al sostre i una planta al costat de la finestra.

Al menjador means in the dining room.

Here, al is a contraction of a + el:

• a = to, at, in
• el = the

So:

• al menjador = a el menjador = in the dining room

Catalan very often puts the place first when setting the scene:

• Al menjador hi ha... = In the dining room, there is/are...

You could also say:

• Hi ha una llum al sostre i una planta al costat de la finestra, al menjador

But the original order sounds very natural because it introduces the location first.

Hi ha means there is or there are.

It is the normal Catalan way to say that something exists or is present somewhere:

• Hi ha una taula = There is a table
• Hi ha dues cadires = There are two chairs

In this sentence:

• Al menjador hi ha una llum... = In the dining room there is a light...

A useful way to think about it:

• ha comes from haver
• hi is a little location-related word that is part of this existential expression

So even if English just says there is/there are, Catalan uses hi ha.

In standard Catalan, hi ha is used for both singular and plural.

So you say:

• Hi ha una planta = there is a plant
• Hi ha dues plantes = there are two plants

That means the form does not change the way English changes from there is to there are.

In your sentence, even though two items are mentioned, standard Catalan still uses:

• hi ha una llum ... i una planta ...

That is completely normal.

Because they are two separate nouns, and each one normally needs its own article.

So:

• una llum = a light
• una planta = a plant

When you join them with i (and), you usually keep the article with each noun:

• una llum i una planta

This is similar to English:

• a light and a plant

If you left out the second una, the sentence would sound incomplete or unnatural in normal Catalan.

Literally, llum means light, but in everyday context it can refer to a light fixture or lamp/light depending on the situation.

In:

• una llum al sostre

it usually means something like:

• a ceiling light
• a light on the ceiling

If you wanted to be more specifically lamp, Catalan might use words like:

• làmpada
• llum de sostre for a ceiling light, depending on context

So in this sentence, llum is a natural general word for the light fixture/light source.

Al sostre means on the ceiling or at the ceiling, depending on how naturally you translate it into English.

Again, al = a + el:

• el sostre = the ceiling
• al sostre = on/to/at the ceiling

Catalan often uses a in places where English might use on or in.

So:

• una llum al sostre = a light on the ceiling

This is very natural Catalan.

Al costat de is a fixed expression meaning:

• next to
• beside
• literally, at the side of

So:

• al costat de la finestra = next to the window

It breaks down like this:

• costat = side
• al costat de = at the side of / next to

This is a very common expression in Catalan:

• La cadira és al costat de la taula = The chair is next to the table

Because the expression is al costat de. The de belongs to the whole phrase.

So you should learn it as one chunk:

• al costat de = next to / beside

Then you add the noun:

• al costat de la finestra
• al costat de la porta
• al costat del llit

Notice that:

• de + el = del
• but de + la = de la

Examples:

• al costat del sofà = next to the sofa
• al costat de la finestra = next to the window

Yes. Catalan often uses definite articles where English also uses them, and sometimes in places where English might be a bit more flexible.

Here:

• la finestra = the window

In a room description, it is very natural to refer to familiar objects with the definite article:

• la finestra
• la porta
• la taula

So al costat de la finestra is exactly what you would expect.

Yes, but the meaning focus changes.

• Hi ha una planta al costat de la finestra = There is a plant next to the window

  • This introduces the plant as something present in the room.

• La planta és/està al costat de la finestra = The plant is next to the window

  • This talks about the location of a specific plant that is already known in the conversation.

So hi ha is used to introduce something, while és/està is more about describing where a known thing is.

For a room description, hi ha is usually the most natural choice.

The word order can change somewhat, but the original version is very natural.

Original:

• Al menjador hi ha una llum al sostre i una planta al costat de la finestra.

Other possible orders:

• Hi ha una llum al sostre i una planta al costat de la finestra al menjador.
• Hi ha al menjador una llum al sostre i una planta al costat de la finestra.

But these can sound less smooth or put the emphasis in a different place.

The most natural room-description pattern is often:

• Place + hi ha + thing(s)

So:

• Al menjador hi ha...
• A la cuina hi ha...
• Al dormitori hi ha...

A couple of pronunciation points are useful here:

• llum: the ll in Catalan is traditionally a separate sound, but in many modern accents it is pronounced like a y sound. So llum sounds roughly like yum or lyum, depending on the accent.
• hi ha: this is usually pronounced smoothly together, and the h is silent. So it sounds roughly like ee-a or ya depending on speech rhythm and accent.

Pronunciation varies a bit across Catalan-speaking areas, so do not worry if you hear small differences. The important thing is to recognize hi ha as one very common expression.