FCR% = % of Number of tickets resolved after the first contact made by the customer divided by the total number of tickets resolved in the selected time period.
First Response SLA% = % of Number of tickets whose first responses were sent within the SLA divided by the total number of tickets whose first responses were sent in the selected time period.
Average 1st response time = Total time taken to send the first response during the selected time period divided by the number of tickets whose first responses were sent in the selected time period.
Kindly go through this link for detailed information about the metrics in Agent Performance Report.