The essence of money is to help humans exchange value across time and space.

Time dimension: Store of Value
Preserving the wealth created today for the future.
Work today, and ten years later you can still purchase goods of similar value.
This is the most important function of money.
Space dimension: Medium of Exchange
Enabling transactions to be completed smoothly between different regions and people.
Whether it's gold, the US dollar, or Bitcoin, they all serve the role of exchanging value across space.
Money is a tool that preserves value over time and transfers value across space. The store of value determines whether money can transcend time, while the medium of exchange determines whether money can transcend space.
If a currency cannot effectively transcend time (long-term preservation of value), it will ultimately weaken its function as a medium of exchange and unit of account in space. Therefore, he places store of value at the top of the three functions of money.