target means that the systemd-service will start when the system reach runlevel 2.

What is multi-user mode in Linux?

A runlevel is one of the modes that a Unix-based, dedicated server or a VPS server OS will run on. Each runlevel has a certain number of services stopped or started, giving the user control over the behavior of the machine. Conventionally, seven runlevels exist, numbered from zero to six.

What are targets in Linux?

A unit configuration file whose name ends in “. target” encodes information about a target unit of systemd, which is used for grouping units and as well-known synchronization points during start-up. This unit type has no specific options. See systemd.