Service Account his use by a machine like prometheux to pull metric from kube API
or jenjins use API to deploy app on the cluster
to create a service account
kubectl create serviceaccount dashboard-sa
kubectl get serviceaccount
when you create a service account that create a token you can see the token with :
kubectl describe serviceaccount dashboard-sa
its store as a secret object
if you need this secret inside the cluster you can automount the token inside a pod