Omni-Channel limits in Salesforce

 To quickly check the limits in the org, go to Limits under Omni-Channel Setup.

Whenever a record is routed through Omni-Channel, Pending Service Routing record is created.

Current Pending Service Routings gives the number of active Pending Service Routing records that are waiting for Agents to pick up.
The Pending Service Routing(PSR ) record is deleted by the system when an agent accepts the work item.

Current Pending Service Routing Rate per Hour gives the number of Pending Routing records that are routed for every hour.