You have to Unlock an administrator account sometimes
Use this command to unlock the account of an administrator that was locked, typically because of multiple incorrect login attempts.
php bin/magento admin:user:unlock {username}
You must specify the administrator’s username. Example:
php bin/magento admin:user:unlock admin
Outcome: The user account "admin" has been unlocked
Source : https://devdocs.magento.com/guides/v2.3/install-gde/install/cli/install-cli-subcommands-admin.html