"The flag's colors are red and white."
Translation:Flagets farver er røde og hvide.
Although "flag" is a t-word, the object they is describing "flagets faver" as opposed to just "flaget", the adjectives have to agree with the plurality of it
Are they describing the word colours or the colours which make up the group of colours?
I read the sentence as The flag's colours are red (colour) and white (colour). Plural would indicate multiple shades of red and white. English doesn't differentiate between those, but in Czech (which requires the agreement of number and category and many more things) we would definitely use singular.
If it is as you say, be it, but I'm just wondering about an alternative explanation of the sentence.
Even though there is only one of each colour, they all come under the plural "colours". The reason why one doesn't differentiate in English, is because colours are never plural in English, in much the same way as the Danish "dyr" is both singular and plural.
My question is whether the sentence could be interpreted as a list of colours which constitute the set. That's how I read it because I'm used to that from my native language. English hides the difference because it doesn't have a plural form of adjectives.†
The sentence is strange (in English), because when we usually describe the object directly (The flag is red and white.) rather than describing an abstract property of the object . A different thing would be a concrete property like in The car's doors are red and white in which case the plural form is apparent: the subject (doors) is plural, adjectives have to be plural.
I've tried to come up with a sentence which would show my understanding of the sentence (because I'm not sure, it's coming across), but all examples end up similarly ambiguous The car's shapes are smooth and round or too different in their nature The team members are Anne and John - Anne and John are members of a set, but they contain the uniqueness which colours (or other adjectives) inherently lack. Still this sentence is the closest example to how I parse it and I am wondering if it is an acceptable interpretation.
† I believe the example you mentioned is not the best one. Because dyr is the same form for both singular and plural, much like English fish and it's a pretty rare thing (at least in English). It's not the same as uncountable nouns where there's no concept of singularity/plurality and it's not the same as a complete lack of plural form because there isn't any use for it. I wouldn't be surprised if there used to be similar distinction between singular and plural adjectives in English and then one faded out (similar to what happened to second person pronouns). Moreover, colours get used in plural form at least informally when they're meant as a shorthand for the objects they characterize; then they behave like nouns instead of adjectives: wide selection of reds and whites. That however is a completely different matter. I just couldn't not mention it.
I actually had a think about the original sentence and actually thought "Flagets farver er rød og hvid" actually sounds better to me 3 months after writing the comment. I also asked a Dane and he agreed but couldn't really explain why, but I believe here "rød" and "hvid" should actually be acting as nouns, naming the colours rather than describing anything which, if I have interpreted it correctly, I think is what you were getting at with your original comment.