What does "nose breath" mean?
"You should not try to find the point where the moving air strokes
  the nostrils, but keep your focus at the nose breath".


This means to not try to feel, track or be aware of the breath sensations. Instead, it means to only keep the mind exclusively focused towards the nose. It means to never concern yourself with watching the breath, even if the breath comes into the mind as an object of awareness. Just keep the mind still &amp; anchored in one place.