What does the idiom 'cut the mustard' mean?

Cut the mustard: to be able to handle a difficult job or fulfill the requirements

If something doesn't cut the mustard, it means that it does not meet necessary requirements or expectations. For example,

"My wife is mad at me for missing our anniversary. I bought her a bouquet of flowers, but that just didn't cut the mustard."

The idiom "can't cut the mustard" means not being able to handle difficult situations.
It means whatever it is is not sufficient, that more is required.
"Can't cut the mustard" means something doesn't meet standard expectations.