if you set a password with enable password command
i.e. enable password cisco
And then run the command show running-config you will be able to read your password as a clear text.
i.e. you will see enable password cisco
This method is not recommended because of security issue
if you set a password with enable secret command
i.e. enable secret cisco
And then run the command show running-config you will be NOT able to read your password as a clear text.
i.e. you will see enable password $1$C/q2$ZhtujqzQIuJrRGqFwdwn71
The password is encrypted here
This method is recommended
This command encrypts passwords, for example if you set passwords in your router such as console or vty passwords and run the show run command you will be able to read the passwords you entered as clear text, but if you inter the command service password-encryption all passwords will be encrypted so no one will be able to read the passwords