Body image simply means the way someone perceives, thinks or feels about his/her physical appearance. It's not just about how a person looks, but it's tying your inner narrative to your look. So, it's necessary to practice a healthy body image as it will allow for acceptance and appreciation.
Having negative thoughts about your body could lead to self doubt, anxiety and harmful behavior. So, you can build your body image by trying to unlearn or do away from false ideas and having respect for your own body.