systemd is an init system used in Linux distributions to bootstrap the user space and manage all processes subsequently, instead of the UNIX System V or Berkeley Software Distribution (BSD) init systems. It is published as free and open-source software under the terms of the GNU Lesser General Public License (LGPL) version 2.1 or later. One of systemd's main goals is to unify basic Linux configurations and service behaviors across all distributions.
From the version 7, Centos also using systemd instead of conventional init system.
This article explains the details of different messages for systemd statuses.
enabled - a service that is configured to start when the system boots
disabled - a service that is configured to not start when the system boots
active - a service that is currently running
inactive - a service that is currently stopped and may be disabled, but it can be started and become active