那是回不去的时光刹那芳华
[nèi shì huí bù qù de shí guāng chà nèi fāng huá]
'That was the time which can never be revisited when beauty briefly shined.' It speaks about the nostalgia for the irretrievable past when one's glory days were momentarily in full splendor, expressing melancholy towards fleeting moments that are now just memories.