Nonce is an abbreviation for “number used once”.
It is a random, disposable number used only once in cryptocurrencies such as Bitcoin.
In mining, one person who wins a computational race can connect the blocks generated by himself to the blockchain and receive a reward.
This computational competition is the process of finding the value of a hashed Nance, which requires the miner to perform a huge amount of calculations.
This calculation itself has nothing to do with the transaction, but only with identifying a random number of nances.
In Bitcoin mining, this task of finding Nance is a waste of electricity and has no economic rationale. Some altcoins have replaced this calculation with a more socially meaningful method.