I want to use [this terminal block][1] on my PCB. However, the schematic and PCB footprint Mouser provides are unclear to me. Why are there 4 pins and what is my signal and ground pin? The data sheet does not provide any detail either. 

EDIT: To provide more context about what I am looking at; this is the footprint Mouser provides:

[![enter image description here][2]][2]

  [1]: https://www.mouser.ca/datasheet/2/418/8/product_1776244_2_datasheet-2517103.pdf
  [2]: https://i.sstatic.net/H790v.png