A Proxy is installed on nodes to allow Kubernetes services to be implemented. This allows for exposing network points to Pods that require it. If this is not a requirement a proxy does not need to be installed.
As Pods are spun up and down as required with differing IP’s a proxy allows a specific Kubernetes services address to be used and the proxy can re-direct this traffic depending on what Pods are currently up.
The default kubernetes proxy is kube-proxy