Kubernetes services (or just called services in the kubernetes world) are an abstraction to allow exposing static endpoints for consumption whilst Pods in kubernetes are constantly changing.
For example a pod might be hosting a database at 1.2.3.4:1000 today and at 4.3.2.1:1000 tomorrow, services allow you to specify an endpoint myservice:80 that the kubernetes Proxy can then re-direct to the appropriate Pods.