The images below are provided as a reference and a guide. If you have a different board, it may not work.
For the BLtouch, there are usually a total of 5 wires. If you have something more or less, you may have something else.
First wire from the top, black, white, yellow, brown and red. If you have a 3D touch instead or any other BLtouch clones, your brown wire may be green instead. It seems like it is also possible to have blue instead of brown wires on recent Genuine BLtouch(s). (updated Jan 2020)
It seems like BigTreeTech has decided to give you an extra 2 pins beside the servo ports dedicated for the BLtouch. However, if you're following the Cheetah 5.0 guide, you should connect it to the Z ports instead highlighted below. It should work as intended.