Basically, earning credits for acts of selflessness in this life improves your chances that your next life will be even better than this one.
It is Yaow's birthday, so Na takes the opportunity to put a marker on the event by taking her to make merit at Bangkok's Wat Yannawa...in addition to performing a number of rituals in the temple building where I cannot use my camera, they also take advantage of the eternally hungry fish in the river and pigeons on the pier.