Dots on a schematic indicate a connection, in this case to ground.
The guard is primarily for PCB mounting of the components. It should be on both sides of all traces that go to pin 2 and 3, on all layers of the PCB. For a trace to pin 2 or 3, for example, it would consist of two additional traces connected to ground, one on each sides of the pin 2 or pin 3 trace.
All guards are connected to the ground connection on the PCB. Think of it as isolation around all the connections to pin 2 and 3. The idea is to drain away any leakage currents from any nearby traces that are at a different voltage from pins 2 and 3.