red

In a sentence

• Я купил красный автомобиль.

  I bought a red car.

  Here, the word 'красный' is used as an adjective describing the noun 'автомобиль', indicating its color.

• На карте красным цветом отмечены опасные зоны.

  On the map, dangerous zones are marked in red.

  In this case, 'красным' is a form of the adjective 'красный', used substantively, referring to the color red emphasizing the marking used.

• Красный — это цвет энергии и страсти.

  Red is the color of energy and passion.

  Here, 'Красный' acts as a noun used abstractly to represent the color itself, indicating symbolic meanings associated with this color.