Extended Puppy Pose (a.k.a Puppy Dog Pose) is similar to Child Pose and can be used as a resting posture during a yoga sequence (instead of Child Pose).
Extended Puppy Pose is a chance to get some rest before the next series of poses. In a yoga class, the teacher will usually get you an Extended Puppy or Child pose after a fast-paced vinyasa sequence, a long hold in a pose like the Downward Facing Dog pose or Plank pose, or a challenging inversion like the Shoulder stand pose. It is a counter pose for the Upward Facing Dog pose and other back extensions like the Cobra pose.