It's a clever breakout board for a chip that talks I2C to drive 16 channels of PWM / Servos.
You would figure that creating simple on/off pulses is a pretty easy thing. Well it is. Watch: On....off.....On.....On..(DANG). Ok, it's pretty simple for a single signal, but if you're wanting to create a bunch of well-timed on/off signals, that gets particularly tricky, even for an Arduino.
Enter the PCA9685, and its breakout board from Adafruit.
Instead of using up your limited number of PWM lines, or trying to fake it all in software (and using up all the resources on your microcontroller), you can simply pop a signal over to this chip via I2C to tell it which of 16 lines you want to pulse, with 12-bit (4096) levels of accuracy. And it'll keep doing it, all by itself. Pretty handy. And the PCA9685 can be chained 62 deep, for a total number of control of 992 PWM output lines - that's impressive!
The kit comes mostly assembled, with a set of 3x4 headers for installation of servo/LED plugs, a 2-pin power terminal block, and a 6-pin 0.1" header for breadboard-compatibility.
This product comes with a fully tested and assembled breakout as well as 4 pieces of 3x4 male straight header (for servo/LED plugs), a 2-pin terminal block (for power) and a piece of 6-pin 0.1" header (to plug into a breadboard). A little light soldering will be required to assemble and customize the board by attaching the desired headers but it is a 15 minute task that even a beginner can do.