When Hannah tells Rabbi Boruch that she is from the future, he says, "All the children are from the future. I am from the past. And the past tells us what we must do." What does this mean?

The Rabbi is referring to the fact that the past often repeats itself...... and that if we've listened to the past and have learned from ...... we may know what to do.

need help

Rabbi Boruch means that him, being the past knows best and Hannah, being the future, needs to learn from the past.