The very first time you log into a new host you will be asked to verify that the system is the one you intended to access. The remote system will send its host key to your client as part of their handshake and your client will ask you to verify the host key fingerprint before continuing the login process. It sounds complicated, but you don’t have to worry about it! Your ssh client does all the work! Here’s an example of what you should see on that first attempt (this will vary based on your OS).