Kubectl explains is useful for a Fission user to write function specs especially but it does not give any information as of now.

$ kubectl explain functions -ndefault
KIND:     Function
VERSION:  fission.io/v1

DESCRIPTION:
     <empty>

It should look something similar to:

$ kubectl explain pod.spec
KIND:     Pod
VERSION:  v1

RESOURCE: spec <Object>

DESCRIPTION:
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#spec-and-status

     PodSpec is a description of a pod.

FIELDS:
   activeDeadlineSeconds	<integer>
     Optional duration in seconds the pod may be active on the node relative to
     StartTime before the system will actively try to mark it failed and kill
     associated containers. Value must be a positive integer.