In the Bitcoin network there is no bank or anyone with the authority to adjust the extracts. There is no central authority. The actual states of the accounts are determined by the consensus of the computational work of the miners. The power of computational processing is creating the blockchain, from there provi.
When a transaction is made and that transaction is retransmitted to the entire network, the existence and veracity of that transaction is not yet confirmed. With the decentralized structure of Bitcoin, the existence of this transaction is confirmed when it is included in the blockchain and new blocks are created on top of the block in which the transaction we have made is confirmed.
At any moment there could be two or more blocks at the same level competing to process the same transaction and become the next block in the blockchain. Some of the blocks will end up being "orphans" and only one will be the "real" one when they grow with more blocks.