A "hot" wallet is a wallet on your desktop or phone connected to the internet, one that can send and receive crypto to other wallets or exchanges. A "cold" wallet is not connected to the internet, and is usually located on a flash drive or similar storage device. As such, cold wallets are impervious to the majority of scams in the crypto world (unless you just... hand it to someone you shouldn't. Don't do that!). The safest wallets are cold, so if you plan to own a large sum of crypto (or already do), then do yourself a favor and secure your investments. Have a hot wallet for transactions and integrations with an exchange, and a cold wallet to store your holdings.