That sounds unintentionally negative. I'm genuinely curious.
There are some technical details like: allowing the diaphragm to expand fully, the ribs to expand, and the collar bones to expand. Other details such as: doing this while relaxed (relaxed enough to let go of volitional control over the breathing while still being aware of the movement), not forcing the breath, where you can't hear the breath.
Hyperventilation, as in, nervous or panic reaction usually coincides with shallow breathing, where the diaphragm and ribs don't move much, if at all. You don't circulate much oxygen. The technique the author is talking about significantly increasing the amount of oxygen circulating in your body.
Finally, the most important point. This isn't something you can dissect from the outside. You try it and experience it.