This board is design to assist with installations with long chains of neopixels. The idea is to use it to chain together your strips like this:

The principal problems it solves are:

• Power distribution (getting power to each strip without dropping voltage across strips)
• Power quality (providing capacitance for each strip)
• Data quality (providing resistors for the data line)

For power distribution, each board has input connector and output pluggable terminal block connectors. This allows for chaining power between multiple boards.

For power quality, neopixels strips need bulk capacitance to stabilise their power rails, the board has 2x330uF capacitors for this. These capacitors draw a lot of surge current when first connected to a power supply, so the board also includes a soft-start circuit that ramps up the power over about 50ms. The reduces peak loads on the supply and reduces ringing.

For data quality, the data line has the recommended 330R series resistor. It also has a 10K pulldown to keep the data line low when nothing is connected.

All in all, it's a simple board that makes life a bit easier and your installations more robust.