Understanding in sync gateway logging

I need more understanding about it like what is the meaning of value on Y axix. what these two numbers mean.
Following is the graph. Machine is running on AWS with 8 Cores ,16 GB RAM , 9 buckets out of which 8 are handled by the sync gateway. with no accelerator. Its a dev envioment where the number of connection are very less netstat -tup gives 711 lines.