I advise you not to cherish noble Yi, and I advise you to cherish youth. When the flowers should be folded, we should fold them quickly, and don't wait for the flowers to wither before folding one.
The lyrics are very shallow and can be translated into: I advise you not to cherish beautiful gold thread clothes. I suggest you cherish your youth. Flowers should be picked in time when they are in full bloom, and it is too late to pick them when there are only branches left after withering.
According to the singer's identity (originally a singer, later became a big bureaucrat's little wife), you can easily understand her intention of singing this song. But on the positive side, it can also be understood as persuading people to cherish their youth and not to waste their time.