Is this likebitcoin and can you buy it on ameritrade
It’s not publicly traded yet. But these early trades are giving some indication of how it is likely to be valued when it does go public. At these valuations it will be several times the size of the company that manages the NYSE.
Coinbase is the largest and best known bitcoin/cryptocurrency exchange for the US. There are a plethora of other exchanges, but this is the one many people start with.
Just remember: Not your keys, not your coins. Unless you are near to trading as asset, it should not be kept on an exchange.