"These pants are black."
To the creators of Duolingo Japanese for English speakers: I humbly request that you include both the kana and kanji in the dotted line help. More times than I can count I've looked for a new word in hiragana, only to find only kanji offered, where there are NO KANJI offered among the solution words. Please.
From French jupon (“petticoat, underskirt”), from French jupe (“skirt”), from old Italian jupa, from Arabic جُوبَّة (jūbba, “long garment”).
Note that the meaning has changed from “underskirt” to “trousers/pants”, and the second consonant has changed from /p/ to /b/, possibly influenced by native Japanese onomatopoeia ずぼん (zubon), describing the action of something sliding, as when one puts on or takes off trousers.
Desu is not necessary. Perhaps it would be worthwhile to think of it as a word without a meaning. It is a polite thing to say for declarative sentences (A is B). But it is not needed, because if you don't include it, the sentence would still mean A is B, so maybe don't think of it as meaning is.
You can have desu at the end of a declaration, or you can use da, which as an informal declarative ending, but not using either is valid, just also informal. I'm not sure if putting nothing or da is least formal but I think having no ending is the least formal way. But, yeah, no verb is required for these types of statements, dunno how or why it is like that, but it is.