Hello and Welcome if you are talking the little V shape missing in the very front, I believe that part of the beak must have broken off. Was it always missing or just recently? Can he still eat okay? As long as he can eat, i wouldnt worry about it. It will/should grow back. Such a cute smiling looking tort.
Be sure to feed the tortoise plenty of calcium-rich foods and allow her to get plenty of sunshine. This will help strengthen the calcium in her body, which has to do with growing beaks, nails and bones.