Label of Selinux

[linux_tux]

What does this mean "system_u:object_r:var_t:s0"?. After reading documentation, i found that they have discussed 5 fields. But my system shows the following:-

[root@clouduser1 ~]# ls -ldZ /var/opt/
drwxr-xr-x. root root system_u:object_r:var_t:s0 /var/opt/

Could someone help me to understand it?