YOLO is a pretrained network to detect 80 objectsfrom an image as mentioned in the.txt file.
yolov3.txt - Contains the name of 80 objects
yolov3.cfg - contains the values of different layers like batch size, filters and more
Download the pre-trained YOLO v3 weights file from this link
python yolo_opencv.py --image Apple\ Tree\ Images/apple-1.jpg --config yolov3.cfg --weights yolov3.weights --classes yolov3.txt