The yoga class focuses on one's "pranayama" or "prana"  which is the breath or vital energy in the body. On subtle levels prana represents the pranic energy responsible for life or life force, and "ayama" means control. So Pranayama is "Control of Breath". The logo is representative of breath coming in through the nostril on your right and leaving your body on an exhale through the left.  It is also representative of the base posture, Padmasana (Lotus).