User Accounts are locked after 5 unsuccessful login attempts.
If a User fails to enter the correct user/password combination it prompts them 4 times with a warning...
If they keep trying and use up the 5 attempts, then they will be locked out...
At this point, the User can wait 30 minutes and try again (you're ok to tell them that, but we purposely do not put that on the login screen), but as an Admin you can immediately go into the People Page and find that user. On their basic tab, you will see a black banner at the bottom the screen where you can unlock their account.
When you click unlock, you will be prompted with a Popup to make sure you want to do this and when you click yes, you will see a notification that the account has been unlocked.
As an admin, you also have the option to change their password. Below you will see a screenshot of what that looks like and where you would enter it on the user's Basic tab.
Note the warning you can receive if the password you enter for them does not meet the password rules...