"The furniture is big."

[tumbleweed67]

How do I know if it's plural or singular? In English the furniture can be both. The suggestion said it as plural and was marked incorrect

[Danmoller]

(I may be wrong in this one)

I believe saying "a mobília é grande" means something different than saying "os móveis são grandes".

Mobília = furniture

Móvel = a piece of furniture

Móveis = plural of móvel. Can be interpreted as furniture in many cases.

But, correct me if I'm wrong, I believe big furniture means many pieces, not big pieces of furniture.

[cloudhorizon]

Well...if I heard someone say "My house has big furniture" I would think that he or she meant that his house had big pieces of furniture. Many pieces would probably be "A lot of furniture" or "I have much furniture" (but that one sounds a bit awkward in conversations)

[Danmoller]

I see....my mistake then.

[7tonyseven]

Furniture can be either singular or plural in English.

[Declan840658]

As a native English speaker, for singular I would always say "piece of furniture", which Duolingo accepts. If I say or hear just "furniture" in a sentence, it implies plural.

[raf_iggy]

The English word "furniture" is singular (requires singular agreement), but can refer to "a" collection of things.

Portuguese has a word that refers to a single piece of furniture and can be made plural to refer to multiple pieces of furniture.
Strange but....
Is "a mobilia" a collection of pieces of furniture?
What is "as mobilias"?

[joatmoo]

Raf_iggy, furniture is used as both singular and plural. You seem to suggest there is no plural. https://englishgrammar.org/singular-plural-nouns/
"Some nouns have only a singular form or only a plural form. Nouns which have only a singular form include the following: furniture, wheat, happiness, scenery, news, information, luggage, bread..."

[peterjoel58]

This is nothing if not confusing. The English says "is", but the translation says "are". It's like that and that's the way it is.