I still can’t figger out what bitcoin is, or isn’t.
A bitcoin is a piece of information. This information has value because it is rare, as it is intrinsically difficult to produce. The information is portable, but not replicable, so it cannot be counterfeited. Due to the nature of the way transactions with this medium are processed, it’s authenticity is verified as part of any transaction, and the proof of the authenticity is secured with encryption that is technologically unfeasible to break.
There is a little more to it than that, but that is a primer.