When people talk about the price of Bitcoin, they are referring to the current price at which Bitcoin is changing hands. Since Bitcoin is a purely speculative asset, this price is determined by how little sellers are willing to charge and how much buyers are willing to pay. Even then, the price of Bitcoin can vary across exchanges like Coinbase and Binance or currencies because of market inefficiencies
Essentially, if you are interested in trading in digital currencies but don't want to get bogged down in the underlying technology, products like Coinbase are a way to begin a foray into a new form of currency speculation and investing. You do, however, lose some of the advantages of trading in a cryptocurrency and through the blockchain. On Coinbase, you have no pseudo anonymity—your name is attached to your Coinbase account and so is your bank account, so transaction history is relatively easy to track down. And if you're not working on the blockchain, there's not much you can do to ensure that the verification of your transaction history or your account is taking place on the blockchain. You are, instead, placing trust in the intermediary, in this case, Coinbase.