UNO R3 + WiFi ATmega328P+ESP8266 (32Mb memory) USB-TTL CH340G For Arduino Uno - External ESP8266 Pins This board have pins to ESP8266's GPIOs.
What is Tout pin ?
On the back of the board it label pins :GPIO12, GPIO02, and another GPIO02 ? a continuity test shows that they are not connected. So what is it ?
From esp8266 datasheet:

TOUT - ADC pin. It can be used to test the power-supply voltage of VDD3P3 (Pin3 and Pin4) and the input power voltage of TOUT (Pin 6). However, these two functions cannot be used simultaneously.

from the pinout PDF of the Uno+WiFi board: