It means moving to a place for a specific action or purpose.
When to use
purposeful movement, planned action, daily conversation
The nuance
Attach -(으)러 to the verb stem followed by 가다 or 오다 to express going/coming for the purpose of doing that action. For example, 먹다 → 먹으러 가다. Use when the purpose of movement is clear. The choice of 가다 or 오다 depends on direction of movement.
