Likely a nickname for a specific player, a clan leader, or a specific location/NPC. In some contexts, it can be a diminutive or localized slang.
Look at your clan or faction chat. Usually, "na sbor" refers to a specific Teleport (TP) point or a "Combat Zone" entrance. ork_marica_na_sbor
Common for "ZvZ" (Zerg vs. Zerg) content where an "Orc-style" (melee-heavy) group gathers for a fight. Likely a nickname for a specific player, a
If you have been told to follow an "ork_marica_na_sbor" instruction, it usually involves these steps: a clan leader