The Serial Monitor can be enabled or disabled via the ESPEasyFlasherConfig.json. For enabling you have to use the following setting:

   "serialMonitor" : true,

For disabling:

   "serialMonitor" : false,

With the On/Off button you can start or stop the Serial Monitor. The received messages from the ESP over the serial connection will be shown in the textbox below the Serial Monitor Control Area. In the screenshot below, you can see the incoming messages of the ESPXXX_jQuery_Mobile_Interface.eef example after ab reset if the ESP microcontroller.

If the Serial Monitor is started, you have also the possibility to reset the microcontroller with the button "ESP Reset". This makes sense if you need messages after the reset of the ESP or the microcontroller is in a housing and the reset button on the developer board can not be reached.