SainSmart MEGA 2560 Board for Arduino:
This is a microcontroller board based on the ATmega2560. It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

SainSmart Prototype Shield V3 processes technology, motherboards, small gold square pad spacing, welding components easier. SOP28 SMD component package to be more handy electronics enthusiasts will not be directly insert bound components.

The board can not only receive MEGA seamless plug controller, directly soldered to the above components to complete a variety of prototype circuit, you can paste Mini bread board, through the 7-color jumper to complete a variety of circuit experiment , board integrated power indicator and status lights, and reset buttons, easy to learn MEGA preferred prototype controller expansion board.

L293D is a monolithic integrated, high voltage, high current, 4-channel driver.
Basically this means using this chip you can use DC motors and power supplies of up to 36 Volts, thats some pretty big motors and the chip can supply a maximum current of 600mA per channel, the L293D chip is also what's known as a type of H-Bridge.