These are completed orders for customers who chose in-store pickup, waiting for the customer to arrive and collect them.
Go to Dashboard > Workflow > Order Workflow and look for the In Store Pickup column, or Dashboard > Orders > In Store Pickups for the day`s pickup list.
Once the customer collects their order, mark it as complete. If they do not show up, you can mark it as not picked up rather than leaving it sitting in this stage indefinitely.