Some types of brackets come as standard with built-in hooks pointing towards the gum, which gives them a rectangular shape with one protruding corner. These hooks are used for attaching elastics, which may be needed at various stages of treatment.
Even if your orthodontic plan doesn't initially include wearing elastics, they are an important auxiliary that can be added if needed. For this reason, hooks are built into many types of brackets, and the mouth has to get used to them, as they can't be removed. If they irritate your cheeks or lips, we recommend temporarily covering them with orthodontic wax to ease the discomfort.
This answer is for general information. Your own case needs an examination by an orthodontist.