This is the 6145th most frequent Catalan word.
luz
"Luz" is not a Catalan word; it's Spanish for "light."
In this sentence, 'llum' (translating to 'light' in English) refers to the electrical illumination provided by a bulb in the room.
La llum de l'habitació s'ha fos.
The light in the room has burned out.
Here, 'llum' refers to sufficient brightness or illumination necessary for reading.
Necessitem més llum per llegir millor.
We need more light to read better.
In this usage, 'llum' pertains to natural sunlight filling the home.