Since #Joomla 3.8.8, the βSend Passwordβ option in the User Manager will no longer be enabled by default on new Joomla installs. Up until Joomla 3.8.8, this setting in the "on" position would include a plain text display of a new user's password in the registration email received after creating a new account.
If your site was created with Joomla version 3.8.7 or prior, and you have not set this setting to "no" you should consider doing so. How to change the "Send Password" setting to "no" is what today's #maintenancemonday is all about.