The large letters on the sign mean "Etiquette for using the handwashing water," and the sentence on the right hand side of the sign (where the message begins) reads "Let's clean our hearts and bodies when praying to the kami."  (Kami is often translated as "god," but might be better translated as "spirit," since it's meaning is somewhat different in nuance than the word "god in the Judeo-Christian tradition.)  The sign provides children step-by-step instructions how to wash their hands, starting with the left hand, then the right hand, then drinking the water with the left hand, washing that hand once again, then using the remaining water to clean the dipper handle holding it in both hands.

The point of these instructions is not just empty ritual, but, as the sign says at the end, "In using this etiquette for handwashing, it is very important that you are being thoughtful in taking the water in manner that will leave the next person feeling good."  In other words, th point is not only to purify oneself, but to do it in a way that the next person to use the water will not feel uncomfortable.  This picture can be used in various ways, ranging from teaching about etiquette and the role of ritual to raising the question as to why the sign is necessary in the first place.