you need to cut it after it goes through the 2 mechanisms~
the cable should end an inch or so below the clamping-hex-tighten-able mechanism thing.
1. make sure metal cable is inside black plastic "housing"
2. black housing should end on the very top (first) mechanisum with metal wire going through only
3. metal cable goes through the hex bolt tightenable mechanisum and comes out from the bottom
4. tighten hex bolt while you clamp your brake pads together with your hand
5. cut the cable that sticks out to fit
*optional 6. put the ... protector metal "cable end" and plier it down to clamp down the end of the metal cable to prevent fraying
fk i wrote all this and realized you should probably google a youtube video on how to install brake. i think i've seen a "park tools" one on how to install brake. sry my youtube doesnt work. cant link you. cheers!