Cantonese-flavored set phrase, often heard in Hong Kong/Guangdong contexts. Mandarin has the more common 勤俭节约 for the same idea - choose 知悭识俭 for southern register or to praise an instinctive frugality.
memory
Parallel structure: 知悭 (know stinginess) + 识俭 (recognize thrift). 知 and 识 are near-synonyms, as are 悭 and 俭 - the four syllables hammer in 'knowing-how-to-save' from two angles.
