Started hearing some knocking coming from under the hood recently. Popped the hood to try to find where it was coming from and it was very obvious. My farthest left spark plug wire (where it attaches or kind of suctions to the top of the motor there) was moving in sync with the knocking noise, like something was being bumped. What does this mean?

The spark plug might have become unscrewed from the head or at least is leaking. Need to pull it to see what happened. Do it now. Don't drive until it is fixed.