To mine a cryptocurrency is to perform some task that causes the generation (issuance) of some quantity of cryptocurrency to oneself.
Historically, mining was the metaphor introduced by the Bitcoin cryptocurrency to explain the process by which Bitcoin users would waste electricity and computer hardware and computing time to force the Bitcoin system to issue Bitcoin tokens to them. That mining system is called a "Proof-of-Work" (PoW) system. PoW systems are [wasteful, ecocidal, and nobody should ever operate them].
PoW is also used as a computing technique to solve the problem of event-ordering in the blockchain software. Thankfully, PoW event-ordering has been obsoleted since about 2014, and we have multiple alternatives of event ordering techniques that consume almost no resources, such as PoS (Proof-of-Stake) and DPoS (Delegated Proof-of-Stake) systems.
As for token issuance, the state-of-the-art is the Universal Basic Income (UBI) methodology of Crypto UBI. Instead of inflating the cryptocurrency supply to give tokens to people who needlessly consume the ecosphere, or to give tokens to people who have the most tokens, we simply distribute any tokens that are generated equally among all human users of the system.