What exactly does the "four don't borrow" handed down from the ancients mean?

First of all? Four don't borrow? It refers to cribs, crutches, medicine cans and pig-killing knives. The crib has the meaning of inheriting incense, and borrowing it loses this meaning. A crutch is a symbol of longevity, and there are treasures at home. Pig-killing knives were very dangerous in ancient society. In order to prevent others from being implicated in killing themselves, don't borrow a pig-killing knife. Medicine cans also represent diseases. It is unlucky to borrow someone else's medicine jar, and it is inevitable that there will be residues in the boiled medicine. If it is not cleaned, the consequences will be very serious.