A Kubernetes Service is a collection of several pods running inside a cluster. These services have a policy by which you could access theses pods, and you can have as many Kubernetes service as you require.
Check out the Kubernetes training from Intellipaat which is a course of 10hrs with 20hrs for projects and exercises to help you gain the required hands-on experience.
Also, do check out our YouTube video to help you get started with the Kubernetes training.