Connector question - New guy 1st post

[TheHamburglar3]

Hello everyone, new guy here, I just got handed down an 87 GN, approx 114,000 miles. It was my Grandmother's, and then it was maintained (almost never driven) by my dad, now mine. Looking over the engine, I noticed this green and black connection. Any idea what it is? Sitting behind the alternator.

Thanks for the help. Been doing a lot of reading.