Three-piece system: header, housing, terminal
The 1-770873-0 is a vertical through-hole header from the Mini-Universal MATE-N-LOK series, with 3 positions on a 0.163" (4.14mm) pitch. It mates with the corresponding Mini-Universal MATE-N-LOK receptacle housing (sold separately) and accepts the matching crimp terminal — it's three parts, not one.
Board lock anchors the solder joints
Once soldered, it provides mechanical strain relief for the through-hole solder joints, reducing the risk of cracked joints from cable pull or vibration. The contact length - post of 0.175" (4.45mm) is the solder tail length that goes through the PCB. The insulation height of 0.531" (13.50mm) is the height of the header body above the board — account for this in your enclosure clearance.