This is posture is called paschimottanasana and it´s one of those most basic yoga poses, which we should practice everyday. Thanks to its cooling effect, this asana is particularly useful in the summer when the air temperature goes higher.
This forward bend is soothing, calming and very stretchy - actually the back of the whole body is intensely stretched. A good stay in this pose massages the heart, the spinal column and the abdominal organs, which feel refreshed and the mind is rested. From another aspect, lengthening the backside of your body frees you from the past and helps you to live right here and now.
Tips: If your hands don´t reach your toes you can use a belt or similar. You can also lift your hips with a pillow if that helps you in this pose.