Sanna (pere arise together with feeling (vedana) and is a "marker" of sign and a "recognition" of the mark (sign). It can be used to protect/develop and understand mind's dynamic. What is needed for a beginner = mindfulness of the body.
This is the afternoon guided meditation and talk by Ayya Anandabhodi from the monastic daylong program Entering the Heart of Practice with Ayya Santacitta and Isabelita Papa (Qigong)