It's just the harness for the fan. You're installing a larger diameter wire for the fans, and after doing this you can install a 40 amp fuse into position f44. the thicker wire can handle the 40 amps after installing the new aux harness. Sounds like you need to remove a plug in on the bootm of the fuse panel, open up the connector, and install a wire in the new harness into the present connector.
Sounds a little involved.

Gilly