This is WiFi serial transceiver module, based on ESP8266 SoC.  The SOC has Integrated TCP/IP protocol stack.

Please note this is ESP-12E which replaces ESP-12
 

ESP8266 is a highly integrated chip designed for the needs of a new connected world. It offers a complete and self-contained Wi-Fi networking solution, allowing it to either host the application or to offload all Wi-Fi networking functions from another application processor.

 
ESP8266 has powerful on-board processing and storage capabilities that allow it to be integrated with the sensors and other application specific devices through its GPIOs with minimal development up-front and minimal loading during runtime. Its high degree of on-chip integration allows for minimal external circuitry, and the entire solution, including front-end module, is designed to occupy minimal PCB area.

You can purcharse the break-out board for ESP-12 for making it breadboard compatible 
 
Corresponding Interface:

•     SDIO 2.0, SPI, UART
•     32-pin QFN package
•     Integrated RF switch, balun, 24dBm PA, DCXO, and PMU
•     Integrated RISC processor, on-chip memory and external memory interfaces
•     Integrated MAC/baseband processors
•     Quality of Service management
•     I2S interface for high fidelity audio applications
•     On-chip low-dropout linear regulators for all internal supplies
•     Proprietary spurious-free clock generation architecture
•     Integrated WEP, TKIP, AES, and WAPI engines

Specification:

•     802.11 b/g/n
•     Wi-Fi Direct (P2P), soft-AP
•     Integrated TCP/IP protocol stack
•     Integrated TR switch, balun, LNA, power amplifier and matching network
•     Integrated PLLs, regulators, DCXO and power management units
•     +19.5dBm output power in 802.11b mode
•     Power down leakage current of <10uA
•     Integrated low power 32-bit CPU could be used as application processor
•     SDIO 1.1/2.0, SPI, UART
•     STBC, 1×1 MIMO, 2×1 MIMO
•     A-MPDU & A-MSDU aggregation & 0.4ms guard interval
•     Wake up and transmit packets in < 2ms
•     Standby power consumption of < 1.0mW (DTIM3)

Resources:

• Arduino Code
• For detailed information on this module visit here