那时年少不懂岁月忧伤那时轻狂不懂青春感伤
[nèi shí nián shăo bù dŏng suì yuè yōu shāng nèi shí qīng kuáng bù dŏng qīng chūn găn shāng]
Back when we were young, we didn't understand the sorrow that came with age and didn't grasp how youthful folly brought its own kind of sorrow. Recounts a reflective view of youth, expressing regret and nostalgia.