Yes, hitting or slapping one's own face can be considered a form of self-harm. Self-harm refers to intentionally inflicting physical harm on oneself as a way to cope with overwhelming emotions, stress, or difficult feelings. In this case, the person you mentioned is using hitting or slapping their face as a way to deal with anger.
While the intention may be to release pent-up emotions or cope with anger, self-harm is not a healthy or constructive coping mechanism. It can lead to physical injuries, increased emotional distress, and further exacerbate the underlying issues.
If someone is using self-harm as a coping strategy, it's essential for them to seek help and find healthier ways to manage their emotions. Encourage the person to talk to a mental health professional, such as a therapist or counselor, who can help them explore the root causes of their anger and provide them with more effective coping strategies.
In the meantime, you can support the person by being understanding and non-judgmental. Encourage them to talk about their feelings and offer to help them find resources for professional support. Remember that addressing self-harming behavior requires professional guidance, and your role is to provide a supportive environment while they seek help.