蓝色 + (的) + Noun
The noun 蓝色 (lánsè) means "blue color" or simply "blue." Like other color words ending in 色, it can modify a noun directly or with 的 to describe something's color.
他穿了一件蓝色的外套。
Tā chuānle yī jiàn lánsè de wàitào.
He wore a blue coat.
天空是蓝色的,特别好看。
Tiānkōng shì lánsè de, tèbié hǎokàn.
The sky is blue and looks especially beautiful.
我想买那条蓝色的围巾。
Wǒ xiǎng mǎi nà tiáo lánsè de wéijīn.
I want to buy that blue scarf.