Whats the technical/database entity of a crypto-currency / Bitcoin? I know that Bitcoin accounts are public private keys combination.

Is it the same with the currency? Is one Bitcoin a combination of public pvt key? Or is it a token?
A bitcoin, as defined in the whitepaper, is a chain of digital signatures. "To own 1 bitcoin" is by definition equivalent to the following: "in the history of transactions, as defined by the heaviest blockchain branch originating from the genesis block, there exist unspent transaction outputs that sum up to 1 bitcoin such that you have the private key(s) required to spend them".