kube-state-metrics is a simple service that listens to the Kubernetes API server and generates metrics about the state of the objects.
The exposed metrics can be found here:
https://github.com/kubernetes/kube-state-metrics/tree/master/Documentation#documentation.

The metrics are exported on the HTTP endpoint /metrics on the listening port.
In your case, {{ template "kube-state-metrics.fullname" . }}.{{ .Release.Namespace }}.svc.cluster.local:{{ .Values.service.port }}/metrics

They are served either as plaintext or protobuf depending on the Accept header.
They are designed to be consumed either by Prometheus itself or by a scraper that is compatible with scraping a Prometheus client endpoint.

