If you use Ansible to manage servers, you should probably use ssh keys to do so. Ssh keys are a way of authenticating to a server, like passwords are. Ssh keys can be protected with passwords or they can be passwordless. If you’re using them for automation, you might need to use passwordless ssh keys, but otherwise, it’s a good practice to protect the keys as well.
You can create a key, or really a ssh key pair with the command