最羡少年春薄衫最美不过少年笑
[zuì xiàn shăo nián chūn bó shān zuì mĕi bù guò shăo nián xiào]
Translated into English, it would mean, 'Nothing compares to a boy in the springtime in his thin shirt laughing.' It expresses admiration for the beauty and vibrancy associated with young males especially when depicted amidst the season of renewal like Spring.