Hand over fist usually means rapidly and in large amounts, especially when talking about making money. If a business is making money hand over fist, it is earning a lot very quickly.
The expression is widely linked to physical movement. Imagine someone climbing a rope or hauling a line by moving one hand past the other again and again. That repeated motion creates a strong image of fast progress, which helps explain the modern meaning.
Today, the phrase is most often used with money, profits, or sales, but the core idea is still speed and abundance.
- The company was making money hand over fist after its new product launched.
- During the holiday rush, small shops took in cash hand over fist.
It is a vivid idiom, not a literal description. In modern English, people usually use it to emphasize how quickly wealth, revenue, or business success is growing.