Control livolo switch (NOT the one with remote)

Hi all,

I saw there is another topic about livolo but is about the ones that have a remote control.

I found this

and wondering if someone have more details about how is done


The video shows a board with ESP-12F WiFi module and (externally powered) 3.3volt buck converter.
The ESP-12F seems to control two opto couplers.
Not sure what the opto couplers are for.