"The bean is red."

Translation: Die Bohne ist rot.

[Hortencia634547]

why is it rot instead of rote

[coto.i]

Because the adjective is declined only when it accompanies the noun - in a construct like "(ARTICLE) ADJECTIVE NOUN" (die rote Bohne).

In a construct like "(ARTICLE) NOUN ist ADJECTIVE." the adjective is invariable.

[Margot116152]

This now makes even less sense.

[CapnDoug]

What coto.i is saying is that attributive adjectives, (which sit immediately before the noun) are changed depending on the noun. Predicate adjectives (which follow a linking verb and modify the subject) remain in their base form.

For example: Grüne Bananen sind grün. - Green bananas are green.

[StephenJam5077]

Should the colour not be capitalised, then? The answer gives it lower case.

[CapnDoug]

No, adjectives are not capitalized.

[GeoSchribs]

Es ist eine rote Bohne - die Bohne. Es ist ein blonder Mann - der Mann. Es ist ein weißes Pferd - das Pferd (horse).