There may be many reasons why your dog is afraid to approach. It may have had unpleasant experiences, such as being abused or beaten. This will make it fearful and apprehensive of new environments and people. It may not have received enough social training, causing it to not communicate and get along well with people.
It may have a hereditary fearful personality, making it more likely to be afraid of new environments and people. It may have some kind of medical problem that is causing it to feel uncomfortable, such as pain or discomfort. If you want to help your dog overcome its fear, it is recommended that you seek guidance from a professional trainer or veterinarian. They can help you understand your dog's specific situation and provide training and treatment options suitable for your dog.