Help understanding this Circuit
Whether the relay latches or resets depends on the polarity that you put on the coil. That version was meant to be used with AC, and the terminal that you use, either pin B or pin 8, determines the polarity by way of those diodes.

If you look on page 2 of the datasheet, right below the unit in question is a unit without diodes, meant to be used with DC. Notice it is the polarity of the DC that determines whether the relay latches or resets.