Bitcoin isn't attached to a state or government, so itu doesn't have a central issuing authority or regulatory body, bassically, that means there's no organizational deciding when to make more bitcoins, digiring out how many to produce, kering track of where they are, so how does bitcoin work as a currency ?
This is how Bitcoin works as a currency, it is designed to be a decentralized digital currency that doesn't need any central authority to transfer funds to another person (peer to peer) unlike fiat currency that needs a bank or bank account to transfer funds. The blockchain where Bitcoin relies are the ones who control on how many coins to produce, the block rewards and the halving that being rewarded to miners are all coded on its blockchain, this is why Bitcoin doesn't need any central bank to work. But of course there will be a time that it will stop creating new coins because it is set to have a fix supply, unlike central banks that continuously print a new paper money.