Pods CPU Usage shows as: cores (%), should be something else

[peienluo]

Pod usage = sum (rate (container_cpu_usage_seconds_total{image!="",node="^$Node$",namespace="$Namespace"}[5m])) by (pod)

In the graph, it shows as cores (%), with its meaning quite vague. The number shows a total percentage usage of all cores or something else? (suppose there are 4 cores, number 1% means what?)