This is Evaluation board for ESP-12. Board comes with a ready soldered ESP-12 soldered to it and all the pins are available to the left and right of the ESP-12 board. In addition the TX, RX and GND are available at the bottom of the board. There is also a jumper which you close for programming the firmware and open to run the firmware.
The application code is usually stored on an external NOR flash device; for a typical application 512kB is more than enough. The flash is accessed through a cache; about 35kB internal SRAM is available to the user for stack and temporary storage.
ESP8266EX is typically used in applications ranging from smart switches, smart lighting, smoke detectors, gas sensors, temperature-humidity sensors, smart displays, etc.