05 prius pulled cable from 12v battery

The wire originally is manufactured with a metal terminal crimped on the end. The plastic connector is designed so the metal terminal is inserted into it and part of the plastic deforms as the terminal slides by. Once the terminal reaches the correct position, the deformed plastic clicks back into its normal position, locking the terminal in place. You can usually use a very small jewelers screwdriver to push that plastic section out of the way to remove the terminal from the plastic connector. It's unlikely you'll be able to un-crimp the terminal, but you can just strip a little insulation off the wire and solder the wire to the terminal. Then slide the terminal back into the plastic connector until it clicks into place.

 

That is probably the voltage sense wire that tells the hybrid vehicle ECU what is the battery voltage. The ECU uses that to determine what output voltage the DC/DC converter should provide. If the car becomes READY, you can drive the car in its current condition.

 

Just go to auto parts store and get a ring terminal and crimp that to the wire.
See the nut to the left of the white plug the one that's vertical that nut holds that whole black fuse assy onto the terminal that's bolted to the battery post. Unbolt that nut place your ring terminal on that bolt and then put the nut back on. In doing that u are bypassing the 5 amp fuse in that black plastic assy but that's ok never heard anyone blowing that fuse on that sense line

.Btw there is also a 100 amp fuse that services the big black wire in that black plastic assy. That wire is attached to the underhood black plastic fus box jump points.