Provide a source and destination.

$ kubectl cp POD_NAME:PATH POD_NAME:PATH

e.g.

$ kubectl cp /tmp/foo <some-pod>:/tmp/bar

From CLI help:

Copy /tmp/foo local file to /tmp/bar in a remote pod in a specific container

$ kubectl cp /tmp/foo <some-pod>:/tmp/bar -c <specific-container>

More help:

$ kubectl cp -h
Copy files and directories to and from containers.

Examples:
  # !!!Important Note!!!
  # Requires that the 'tar' binary is present in your container
  # image.  If 'tar' is not present, 'kubectl cp' will fail.
  #
  # For advanced use cases, such as symlinks, wildcard expansion or
  # file mode preservation, consider using 'kubectl exec'.

  # Copy /tmp/foo local file to /tmp/bar in a remote pod in namespace <some-namespace>
  tar cf - /tmp/foo | kubectl exec -i -n <some-namespace> <some-pod> -- tar xf - -C /tmp/bar

  # Copy /tmp/foo from a remote pod to /tmp/bar locally
  kubectl exec -n <some-namespace> <some-pod> -- tar cf - /tmp/foo | tar xf - -C /tmp/bar

  # Copy /tmp/foo_dir local directory to /tmp/bar_dir in a remote pod in the default namespace
  kubectl cp /tmp/foo_dir <some-pod>:/tmp/bar_dir

  # Copy /tmp/foo local file to /tmp/bar in a remote pod in a specific container
  kubectl cp /tmp/foo <some-pod>:/tmp/bar -c <specific-container>

  # Copy /tmp/foo local file to /tmp/bar in a remote pod in namespace <some-namespace>
  kubectl cp /tmp/foo <some-namespace>/<some-pod>:/tmp/bar

  # Copy /tmp/foo from a remote pod to /tmp/bar locally
  kubectl cp <some-namespace>/<some-pod>:/tmp/foo /tmp/bar

Options:
  -c, --container='': Container name. If omitted, use the kubectl.kubernetes.io/default-container annotation for
selecting the container to be attached or the first container in the pod will be chosen
      --no-preserve=false: The copied file/directory's ownership and permissions will not be preserved in the container

Usage:
  kubectl cp <file-spec-src> <file-spec-dest> [options]

Use "kubectl options" for a list of global command-line options (applies to all commands).