Hardware wallets are physical devices where you ‘store’ your Bitcoin or other cryptocurrencies. Your Bitcoin or cryptocurrencies are still stored on the blockchain but the hardware wallets acts like gateways to interact with your wallet.
The private and public keys to your wallets are also stored on the hardware wallet. And in order to move your funds from the blockchain you need to use that specific hardware wallets.
Hardware wallets are also very difficult to hack, they can’t get any viruses or malware. That makes them the safest wallets to store your Bitcoin or cryptocurrencies at.