What percentage of Bitcoins are held by exchanges? was wondering how much is held by exchanges vs. hard wallets (which I dont really understand) how does someone with a hard wallet sell their Bitcoin?
was wondering how much is held by exchanges vs. hard wallets


It's not possible to know for certain how much bitcoin is currently held by exchanges as it is trivial to create pseudo-anonymous addresses and it is generally good practice for an exchange to not disclose their addresses.


  how does someone with a hard wallet sell their Bitcoin?


By "hard wallet", I assume you meant hardware wallet instead. 

A hardware wallet is usually used to interface with software installed on an online machine to sign transactions. The key advantage with using a hardware wallet is that the private key (if properly implemented) never has to leave the device. Once the transaction is signed, then software on the machine connected to the internet may broadcast the transaction to the bitcoin network.