Learn French: Le paysage est brut, sans arbre ni fleur. - The landscape is raw, without trees or flowers.

When using the negative coordination sans... ni... (without... or...), you generally drop indefinite articles (un, une, des) and partitive articles (du, de la). The nouns are used completely bare.

The English translation says 'trees or flowers', so why are arbre and fleur singular in French?

After sans, nouns are usually singular when you mean 'without any' of that thing, unless the object naturally comes in sets (like shoes or glasses). Since a landscape could lack even a single tree, the singular is preferred here.

Could I use brut to talk about raw food, like raw meat?

No, for uncooked food you would use cru. brut means raw in the sense of being natural, unrefined, or rugged, which perfectly describes this untouched landscape.