The following sections assume that you are familiar with the basic concepts of Kubernetes. This https://www.redhat.com/en/topics/containers/what-is-kubernetes article is giving a good overview on Kubernetes and its core concepts. For further reading we recommend the official Kubernetes documentation:
https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/
https://kubernetes.io/docs/concepts/overview/components/
https://kubernetes.io/docs/concepts/workloads/pods/
https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/
https://kubernetes.io/docs/concepts/services-networking/service/#proxy-mode-iptables, iptables proxy mode in particular
https://kubernetes.io/docs/concepts/services-networking/ingress/