A blockchain could be a peer-to-peer Database (aka Ledger) of transactions arranged during a chronological order through encryption. Any data recorded within the Blockchain is immutable in an exceedingly way. Immutability adds the trust on the recorded data which makes the Blockchain powerful sure as shooting use cases.
Bitcoin are the assets created through the ledger on Bitcoin Blockchain.
NFTs are the tokens minted through Blockchain and remain recorded within the blockchain for Ownership, Proof-of-Existence & Time-stamping.
Miners add a Block into the Blockchain by adding the new transactions into it and sign it cryptographically after solving a computation challenge. This process is termed Mining. Miners get rewarded by for this go through transaction fees therein Block which is paid by all the users while proceeding with the transaction.